Parasite Diversity and Their Effects on Histological and Biochemical Components of Wallago Attu (Bloch-Schneider, 1801) and Rita Rita (Hamilton-Buchanan, 1822)

Parasite diversity and their effects on histological and biochemical components of Wallago attu (Bloch-Schneider, 1801) and Rita rita (Hamilton-Buchanan, 1822)

A dissertation submitted to the University of Dhaka in fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Zoology (Parasitology)

By SHAHELA ALAM Registration no. 56 Session: 2013-2014 (Re) Department of Zoology (Parasitology) University of Dhaka Dhaka – 1000

June 2016

ALMIGHTY ALLAH

AND

TO MY PARENTS

AND

TO MEMBERS OF MY FAMILY

DECLARATION

I hereby declare that this dissertation submitted to the University of Dhaka for the degree of Doctor of Philosophy is based on own investigation, carried out under the supervision of Professor

Dr. Hamida Khanum, Department of Zoology, University of

Dhaka, and that, this or any part of this work has not been submitted for any other degree anywhere.

SHAHELA ALAM

CERTIFICATE

This is to certify that the dissertation entitled “Parasite diversity and their effects on histological and biochemical components of Wallago attu (Bloch-Schneider, 1801) and Rita rita (Hamilton-Buchanan, 1822)” submitted by Shahela Alam for the degree of Doctor of Philosophy in Zoology (Parasitology), University of Dhaka, Bangladesh, embodies the record of original investigation carried out by her under my supervision.

Dr. Hamida Khanum Professor Department of Zoology University of Dhaka Dhaka – 1000

Bangladesh

CONTENTS

Page No.

ACKNOWLEDGEMENTS

ABSTRACT

CHAPTER-1: INTRODUCTION 1

CHAPTER-2: REVIEW OF LITERATURE 24

CHAPTER-3: MATERIALS AND METHODS 46

CHAPTER-4: OBSERVATION AND RESULTS

4.1 The communities of parasites 58

4.2 Infestation of parasites in different months and seasons 76

4.3 Infestation of parasites in relation to sex of the fishes 98

4.4 Infestation of parasites in relation to length of the fishes 117

4.5 Infestation of parasites in relation to climatic factors 139

4.6 Infestation in relation to the food and feeding habits 151 of the host fishes

CHAPTER-5: PATHOLOGICAL EFFECTS OF THE PARASITES 160

CHAPTER-6: PROXIMATE ANALYSIS OF THE FISHES AND VARIATION 185 DUE TO INFESTATION

CHAPTER-7: GENERAL DISCUSSION 193

CHAPTER-8: SUMMARY 203

CHAPTER-9: BIBLIOGRAPHY 211

APPENDIX 245 ACKNOWLEDGEMENTS

I express my deepest humbleness to Almighty Allah for his mercy and giving me strength to complete this dissertation. I would like to express my sincere gratitude to all those who directly or indirectly supported and contributed to this research work.

First of all, I express my gratitude to my respected supervisor Professor Dr. Hamida Khanum, Department of Zoology, University of Dhaka for her generous co-operation throughout the study. My investigation would never come to the end if she was not with me with her support, valuable advice, constant care and encouragement.

I convey sincere thanks to Chairman Professor Dr. Md. Anwarul Islam, ex-chairman Professor Dr. M.A. Bashar and Professor Dr. Md. Moksed Ali Howlader, Department of Zoology, University of Dhaka for permitting and providing the necessary facilities to continue the research work in the Parasitology Laboratory of the department.

My cordial thanks to Dr. Akhtaruzzaman, Professor, Institute of Nutrition and Food Science, University of Dhaka, for his co-operation during the period of my research work. I am highly indebted to Mr. Shamsuddin Ahmed, Director, Bangladesh Meteorological Department, Agargaon, Dhaka, for providing all the data of climatic factors (temperature, rainfall, humidity) regarding this particular work. I am grateful to Md. Abu Bakkar Siddique, Statistical Officer, Maternal and Child Health Divison, ICDDR’B, Mohakhali, Dhaka for providing me necessary support and cordial co- operation.

I acknowledge my gratefulness to the authority of the University of Dhaka and to the Ministry of Science and Technology for giving me financial support to run and complete my research work. Words are inadequate to express my deep sense of gratitude towards my parents, brother, my husband whose kindness above and beyond the call of duty has greatly lightened the process of completion.

Finally, I owe a debt of gratitude to my friends and the wonderful staffs of the Department of Zoology and other teachers, who directly or indirectly expanded their friendly hands throughout my work. ABSTRACT

In the present investigation, a total of 250 W. attu and 350 R. rita were examined during January 2011 to December 2012 (both from Swarighat, Dhaka) for the investigations on parasite infestation, proximate composition and pathological effects on the hosts.

A total of 11 species of parasites collected and identified from W. attu, one ecto-parasite (Argulus foliaceus) and 10 endo-parasites of which three were trematodes (Isoparorchis hypselobagri, Macrolecithus gotoi, Magnacetabulum trachuri); two nematodes (Contracaecum L3 larva, Cosmoxynemoids aguirrei); one cestode (Polyoncobothrium polypteri) and four acanthocephalas (Echinorhynchus kushiroense, Pallisentis ophiocephali, Acanthocephalus aculeatus, Pallisentis umbellatus).

From R. rita, a total of 9 species of parasites recovered and identified, among them, one ecto-parasite (Lernaea cyprinacea) and 8 endo-parasites of which four trematodes (Notoporus leiognathi, Saccacoelium obesum, Sterrhurus musculus, Clinostomum piscidium); one nematode (Ascaroid larva) and three acanthocephalas (Cavisoma magnum, Corynosoma alaskense, Corynosoma strumosum). The parasite community in both W. attu and R. rita was dominated by trematodes and acanthocephalans comprising 33.31% and 47.9% of the total number of parasites from W. attu and 59.12% and 31.99% of those in R. rita. Among the total helminth parasites recovered, the most numerically dominant acanthocephalan was Pallisentis ophiocephali (14.58%) in W. attu and trematode Notoporus leiognathi (18.26%) in R. rita.

The prevalence of infestation of ecto-parasite was 23.6% in W. attu (59 specimens) and mean intensity of parasite was 3.11 ± 1.47 per infested fish while in R. rita, 24.8% were infected (87 specimens) with a mean intensity of parasites was 3.34 ± 1.62. The prevalence of infestation of endo-parasites was 34.4% in W. attu (86 specimens) and mean intensity of parasites was 1.66 ± 0.24 per infested fish while in R. rita, 64.57% were infected (226 specimens) with a mean intensity of parasites was 2.64 ± 1.12. Regarding the organal distribution, most of the parasites were found to favour the intestine of

the fishes, except Isoparorchis hypselobagri was harboured the swim bladder. The prevalence of infestation in W. attu was observed higher during winter season while in R. rita, the prevalence of infestation was higher in rainy season. The maximum intensity of parasites of W. attu was recorded in winter and in R. rita, that was found in summer.

The effects of modifying factors such as sex, season, length, climatic factors and diet of the hosts on the abundance of parasites were also studied. Among the main food items, small fishes comprised the greatest proportion (27.2%) in W. attu, whereas, in R. rita, it was 18.3%; the crustacean food item was 17.6% in W. attu while in R. rita, it was 4.8%. W. attu and R. rita also consumed aquatic insects, mollusks as additional food. Presence of large variety of small fishes and other invertebrates in the stomach indicated their possibility as “carrier host” of these parasites in both the hosts.

Juvenile Isoparorchis hypselobagri caused massive tissue damages resulting in erosions and formation of tunnels in the musculature, accumulation of moisture, connective tissue dislocation, massive melanization and mixed inflammatory responses in W. attu. The infected liver showed incipient vacuolation, accumulation of melanin macrophage centers and hemopoietic tissue degeneration. Massive pigmentation was also noted in swim bladder of W. attu due to the infection of juvenile Isoparorchis hypselobagri.

The present observation on biochemical analysis presented small variation in nutrient contents between W. attu and R. rita. Protein, fat, moisture, carbohydrate and ash level were higher in non-infected W. attu and R. rita than those of infected.

ABBREVIATIONS

Abbreviations Illustrations

BFDC ------Bangladesh Fisheries Development Corporation

DOS ------Department of shipping

DoF ------Department of Fisheries

GDP ------Gross Domestic Product

TL ------Total length

NOAA ------National Oceanic and Atmospheric Administration

ICES ------International Council for the Exploration of the Sea

BMD ------Bangladesh Meteorological Department

PRECIS ------Providing REgional Climates for Impacts Studies

IPCC ------Intergovernmental Panel on Climate Change

EUS ------Epizootic Ulcerative Syndrome

AFA ------Acetic Formalin Alcohol

AOAC ------Association of official agricultural chemists

CHAPTER – 1

INTRODUCTION

Parasitology has evolved as a distinct field of science and technology from zoological science. In general the parasitic life is highly successful because it evolved independently nearly every phylum of animals, from Protestant phyla to arthropoda and chordates, as well as in many plant groups. In the study of parasites, fishes play an important role as a host. Fishes are the most important host for maintenance of helminth parasite. Fishes not only serve as the host of different parasites but also serve as carrier of many larval parasitic forms that mature and cause serious diseases in many terrestrial vertebrates including man (Schmidt, 1970).

Bangladesh has large number of rivers, bill, haors, lakes, ponds etc. which harbor about 260 species under 145 genera and 56 families of fresh water fishes (Rahman, 1989). Fishes are the main source of protein in the riverine country like Bangladesh. They supply an appreciable part of human nutrition and also play an important role in the economy of Bangladesh. Besides, all dietary essentials, amino acids are present in fish flesh and about 85- 95% of fish protein is digestible (Nilson, 1946). Thus, fish protein is the best animal protein and very much essential for human body development. It was estimated that about 80% of the animal protein comes from fisheries sector and rest 20% from other resources like poultry and livestock. But recently the amount decreased to 60% because parasitic infestation interferes with the protein contents of fish body and decreases the amount of production. Over 10.7 million people are engaged directly or indirectly in inland fisheries production. According to the BFDC report, the fish supplies 49% of annual consumption of protein. But majority of fishes is heavily infected by parasites which decreases the food value, nutritional amounts and also causes mortality. So, study of helminth parasites in this field is so important for human welfare.

In 1998, a National Fisheries Policy was adopted (i) to develop and increase the fish production through optimum utilization of resources, (ii) to meet the demand for animal protein, (iii) to promote economic growth and earn foreign currency through export of fish and fishery products, (iv) to alleviate poverty by creating opportunities for self-employment and by improving socio-economic conditions of fisher folk, and (v) to preserve

1 environmental balance, biodiversity and improve public health. The Policy extends to all government organizations involved in fisheries and to all water bodies used for fisheries. It includes separate policies for inland closed water fish culture and for coastal shrimp and fish culture. The Policy touches on many contentious issues. For instance, it addresses conflicts over shrimp cultivation and underscores the need for formulation of suitable guidelines. To help conservation efforts, it prescribes a moratorium on further cutting of mangrove for shrimp cultivation. It also supports an integrated culture of fish, shrimp and paddy in paddy fields. In addition, the Policy deals with many other relevant issues such as quality control, industrial pollution and the use of land.

In several years, particularly parasitic diseases have decreased the production of inland fish. Government statistics show that the per capita fish intake has declined from 12kg per annum in 1960 to 7.9 kg per annum in 1986 indicating that fish production could not keep pace with increasing population. According to DOS, total inland fish production in 1996-97 was 10.79 lakh metric ton. Among them, 6.05 from open water resource and 4.74 from close water. About 60% of total animal production comes from fish and close water contributes 28% of the total fish production of the country.

The annual fish production in Bangladesh was 2,701,370 metric tons and fish contributed about 58% to the nation’s animal protein intake (DoF, 2010; Islam et al., 2012; Minar et al., 2012). Fish is an essential and irreplaceable food item in the rural Bangladeshi diet. Fish body composed of mainly water, lipid, ash and protein though small amounts carbohydrates and non-protein compounds are present in a small amount (Cui and Wootton, 1988; Love, 1980; Wootton, 1990; Siddique et al., 2012; Azim et al., 2012). Most of fishes usually consists of water (70-80%), protein (20-30%) and 2-12% of lipid (Love, 1980; Ali et al., 2005). But it may change within and between species and also with size, sexual condition, feeding, time of the year and physical activity (Weatherley and Gill, 1987).

About 56 freshwater fish species critically or somewhat endangered in Bangladesh. A variety of factors such as food, space, temperature, salinity, physical activity influence the growth of fish (Weatherley and Gill, 1987; Ahmed et al., 2012) and the fish body elements may change due to these factors (Kamal et al., 2007). There are a plenty of literatures on the biochemical and nutritional studies of some freshwater fish and some prawn and shrimp species of

Bangladesh (Kamaluddin et al., 1977; Gheyasuddin et al., 1979; Rubbi et al., 1987; Naser et al., 2007; Chakrabarty et al., 2003) and in other countries. But no attempt has been found hence forth to determine the body composition of this endangered fish. More over this fish like other fish of the cyprinid can help to reduce the nutrient demand of the people.

Source of Fish Production

There are three categories of major fisheries resources, these are -

1. Inland Capture (34%) 2. Inland Culture (48%) 3. Marine Capture (18%)

Fisheries sector contributed 4.43% to national GDP and 22.21% to the agricultural GDP and 2.73% to foreign exchange earnings by exporting fish products in 2010-11. Fish provides 60% of national animal protein consumption. Fisheries sector also plays an important role in rural employment generation and poverty alleviation.

Bangladesh has a vast potential for the development of marine, estuarine and freshwater fishes. Its coastline is about 710 km long with about 24, 800 sq. n. miles continental shelf, 2, 640 sq. n. miles territorial water and with 41,040 sq. n. miles exclusive economic zone. In addition, there are 5,332, 657 ha. of water area offered by pond, ditches, oxbow lake, reservoirs, beels, Kaptai lake and flood plain. At present there are 260 freshwater fish species, 12 species of exotic fish, 475 species of marine fish and 60 species of prawn and shrimp available in these waters. Fisheries sector contributes to GDP 5.24%, animal protein supply 63% and foreign exchange earning 4.76% for the nation. If the available fisheries resources are properly exploited through development, fisheries would certainly meet the demand of animal protein for the entire nation.

Parasitism in fish

Parasite is an important group of pathogen causes infection and diseases of fish both in freshwater and marine environments. With the increasing interests in aquaculture parasitic infestations are becoming threats for fish health management and aquatic crop production

3 throughout the world. It is therefore an essential area for proper attention to be given by the scientists for sustainable aquaculture production. The various fishery development programmes depends to certain extent on the successful fish parasitological research, as the improvement of fish yield can mainly be achieved from healthy fish stock. As hosts fishes play an important role for parasites. Among the animals, fishes are the most important host for maintenance of mainly helminthes. Most of the fishes have parasites. They not only serve as the host of different parasites but also serve as carrier of many larval parasitic forms that mature and cause serious diseases in many vertebrates including man. The parasites of fishes cause decrease in growth rate, weight loss and emaciation, affect yield of fish products (liver oil etc), spread human and animal diseases, postpone sexual maturity of fish and mortalities of fish.

Among the fresh water fishes, catfishes are more important because of their food value in many parts of the world, mainly in Asia, Africa and USA. They contain fat soluble vitamin A and B, phosphorus and other important elements. Wallago attu (Bloch and Schneider 1801) is one of the important cat fishes for their voracious and carnivores behavior. They are called “Fresh water shark” because of their predatory behavior, common name is “Boal”. They are not easy to culture because of their voracious feeding habit. They eat floating terrestrial insects, fingerlings, snails, fishes and small mammals (rats, mice). Reportedly (Day, 1878), the longest boal caught was 186 cm in length. In Bangladesh, Rahman(1974), Shafi and Quddus (1982) described the taxonomic identification and characteristics of Wallago attu.

Rita is a genus of catfishes (order Siluriformes) of the family Bagridae. It includes six extant species, R. chrysea, R. gogra, R. kuturnee, R. macracanthus, R. rita, and R. sacerdotum, and one extinct species, R. grandiscutata.

Rita species are found in large rivers throughout the Indian subcontinent and Myanmar. Rita rita is distributed in Afghanistan, Pakistan, India, Nepal, Bangladesh, and Myanmar. Rita species are capable to reach 150 centimetres (59 in) TL; this large size is found in Rita rita. However, mature specimens of about 20–30 cm (5–12 in) SL are more commonly encountered. R. rita is a sluggish, bottom-dwelling catfish. It inhabits rivers and estuaries, preferring muddy to clear water. It also prefers backwater of quiet eddies. R. rita is a carnivorous catfish; the bulk of its diet consists of mollusks. In addition, it feeds on small

4 fishes, crustaceans, insects, as well as on decaying organic matter. Khanum et. al. (2008) studied on community of helminth parasites in Rita rita in accordance to some its biological aspects.

Nature of research done in Bangladesh

Systematics of parasites

Fish parasitological investigation and research performed in Bangladesh have been reviewed through study of available literature. Considerable works mainly on systematics, nature of infestation and pathology of different groups of fish parasites- protozoa, helminths and crustacea have been done. A total of 290 species of parasites have so far been recorded from freshwater and marine fishes in Bangladesh. Ectoparasitic protozoans and monogenetic trematodes are recorded mainly from cultured fish species of farms. Two helminth parasites of zoonotic importance Dibothriocephalus latus and Gnathostoma spinigerum are also reported from Bangladesh fishes. Much attention has been given on caryophyllid cestodes of two catfishes Magur and Singhi. Few fish diseases of parasitic origin have been reported and studied. Commonly occurring parasitic diseases are agrulosis (fish louse), ichthyophthiriasis (white spot) and myxoboliasis. Only few attempts were taken to their control measures using simple chemicals like salt, lime, formalin, dipterex and sumithion. Recommendation has been made for the future works on parasitology for sustainable production of healthy fish (Chandra, 2006).

Protozoa: Several researchers worked out the systematics of this group of parasite. Mostly ectoparasitic protozoans- Ichthyobodo, Chilodonella, Ichthyophthirius, Trichodina reported by Hossain and Barua (1991), Hossain and Khan (1992), Chowdhury (1993) and Banu et al. (1999). Sanaullah and Ahmed (1980) reported myxobolids from Indian major carps and Chandra et al.(1996b) described myxosporeans from juvenile carps of both government and private nurseries of Mymensingh regions.

Helminths: Helminth is a big group of fish parasites belong to Trematodes (monogeneas and digeneans), cestodes, nematodes and acanthocephalans attack the fish both as external parasites (monogenean, few digeneans) and internal parasites.

Monogenea- It is a group of parasites mainly attacks gills and body surfaces of fishes and causes heavy damage. Considerable works have been done on systematics of monogenetic trematodes of fishes by Bashirullah (1973), Hafizuddin and Shahabuddin (1996). Recently significant works on systematics, population ecology and some aspects of histopathology have been done by Chandra et al. (2000a, 2000b), Mohanta and Chandra (2000), Mohanta et al. (2000), Hossain et al. (2000), Chandra and Jannat (2002), Ferdousi and Chandra (2002), Chandra and Yasmin (2003), Begum and Chandra (2003), Ghosh et. al. (2003), and Saha et al. (2003). Most of the monogenetic trematodes are reported from freshwater fishes and only few of them are described from marine fishes.

Digenea- Digenea is the most studied group among the fish parasites of Bangladesh. Bashirullah (1972) described Isoparorchis hypselobagri and noted its life cycle. A number of both marine and freshwater digenens are also reported by Bashirullah (1973), other important works are of Ahmed (1981), Bashirullah and Elahi (1972a, 1972b), Bashirullah and Hafizuddin (1973, 1974, 1976), Chandra (1983, 1984, 1994) and Chandra and Banerjee (1993 a, 1993 b). Golder and Chandra (1987), Golder et al. (1987) studied the digeneans of different fishes and Chandra (1993) recorded digenetic tremtode of estuarine fishes.

Cestodes: Fish cestodes of Bangladesh, mainly the systematic have been studied by many workers. However, histopathology, intensity of infestation and seasonal variations were also studied by several workers. Caryophyllids is a special group of cestode of catfishes (magur and singhi) were given more attention for their study (Ahmed and Sanaullah, 1977, 1979; Rashid et al., 1983, 1984, 1985; Ahmed et al., 1984; Chandra and Khatun, 1993 and Chandra et al., 1997). Khusi et al. (1993), and D'Silva and Khatoon (1997) identified few marine cestodes. Uddin et al. (1980) described Dibothriocephalus latus from Bambay duck (B. loitta), a marine fish of Bay of Bengal and Chowdhury et al. (1982) reported Diphyllobothrid plerocercoid from meni fish of Mymensingh. However, some authors (Hoffman, 1968; Moravec, 1998) termed its presence in Bangladesh as improbable.

Acanthocephala: This is a small group of fish parasite though causes serious injuries and secretstoxins to infested fish. It has received very little attention by Bangladeshi scientists. Ahmed and Rouf (1981), Ahmed and Begum (1978), Chowdhury et al. (1982), Chandra (1985, 1987, 1992a, 1993), Chandra and Rahman (1988) and few others contributed on the systematics of this group fish parasite and described several species.

Nematode: A good number of nematode species have been described equally from marine and freshwater fishes. Bashirullah (1973) reported several nematode species from marine fish. Chandra (1992b) listed the nematodes recorded from freshwater fishes of Indian subcontinent. Bashirullah (1972, 1973, 1974a, 1974b), Ahmed and Begum (1978) and Ahmed and Rahman (1977) studied the systematics of several nematode worms. Bashirullah and Ahmed (1976a, 1976b) observed development of Camallanus adamsi and Spirocamallanus intestinecolisi in the copepod intermediate host. Chandra and Modak (1995) observed the development, activity and penetration efficiency of first stage larvae of Procamallanus heteropneustus in copepods. Mandal (1995) described few nematodes from lizardfishes of Bay of Bengal. Bashirullah (1973) and several other workers (Khanum et al., 1996, Akhtar et al., 1997) reported Gnathostoma spinigerum from a dozen of fish species. This nematode is the cause of gnathostomiasis, a serious disease of man.

In 1964, Vinod Agarwal described the trematodes Allocreadium heteroneustusius, Orientocreadium batrachoides, Haplorchoides macrenis and Eumasenia ritai from the freshwater fishes Heteropneustes fossilis, Macrones seenghala and Rita rita. Bashirullah and Islam (1970) reported a new Phyllodistom Phyllodistomum yousufzaii n. sp. from the swim bladder of siluroid fish Rita rita collected from Sunamganj, Sylhet, Bangladesh. They compared P. yousufzaii with P. staffordi (Pearse, 1924), P. pearsei (Holl 1929) and P. tripathii (Montwani and Srivastava, 1961).

Promas and Daengsvang (1937), gave a report on the life cycle of G. spinigerum. They did an experiment by feeding Cyclops containing 7-30 days old infection to C. batrachus, encysted larvae were recovered in the musculature of the stomach, intestinal, mesentries and in the body musculature. Based on the finding, the authors concluded that C. batrachus is a second intermediate host for G. spinigerum.

There has been changed in the environmental condition in Bangladesh since 1970s. Therefore it may change the parasite fauna of R. rita due to excessive use of inorganic fertilizers and pesticides in cultivated lands, discharge of industrial effluent, inadequate waste disposal etc. which indirectly cause changes in the aqua-environment. The host, the pathogen and environment are in a constant state of flux, capable of changing in any step with any variation in any of these components and thus new infection of parasite may occur in R. rita.

In Bangladesh rain falls in almost all the seasons of the year. The ponds, rivers, haors, bills and other water bodies then get filled with water. The rainy season is favorable for helminth infestation. At this time parasite infects aquatic animals (fish) frequently. Catfishes are also infected by several parasites at this time. W. attu is infected by various parasites due to their voracious feeding habit. It is generally accepted that the parasite fauna in a aquatic ecosystem is determine by the interaction of various biotic forces, and the ecological changes in habits of the organisms living which will be reflected in the parasitic fauna. In this context, little is known about the life history of the parasites to co-relate the occurrence of specific parasites with specific food items. But the correspondence of changes in parasite incidents with change of incidence in the classes of food items examined indicates, to some extent, the group of organisms that may serve as intermediate hosts for specific parasites (Scott, 1975).

Das and Moitra (1955) studied the food of some common fishes of Uttar Pradesh, India and concluded that the food of the surface feeders mainly consisted of algae, rotifers, crustaceans etc. The food of the middle-feeders composed of algae, aquatic plants, adult crustaceans, insects, fish and fish scales. The food of the bottom feeder fishes composed of decomposed aquatic vegetations, fish scales, sand and mud.

The parasites play a crucial role in maintaining the ecosystem balance with relation to all living creatures. Every living creature considered by parasitism either as a host or as a parasite (Combes, 1995). Besides, the parasite is a very important constituent of global biodiversity (Poulin and Morand, 2004). The parasitic copepods have a very significant biodiversity and parasitize practically all groups of marine animals. So they play a vital role in biodiversity, balance and functioning of marine ecosystems. On the coasts of Tunisia,

8 the studies on ecto-parasites are quite numerous. Researches on copepods biodiversity in Tunisia were done by Essafi (1984), Benmansour and Ben hassine (1997; 1998), Benmansour (1995; 2001), Yamak (2000), Djait (2009) and Souidenne (2011).

Argulus foliaceus is a freshwater fish ecto-parasite that has been reported throughout temperate regions of Europe, Central Asia and North America. It has been well studied in Europe, especially the British Isles, where is has had major impacts on UK sport fisheries through fish stress and mortality (Harrison et al., 2006; Oktener et al., 2007; Pasternak et al,. 2004). Argulus foliaceus is an obligate parasite, requiring host availability. This louse has a low host specificity, so it can infect a variety of fish within its habitat (Harrison et al., 2006; Pasternak et al., 2000; Taylor et al., 2006).

Argulus foliaceus is rare in the winter and has been described as having a short lifespan. There is no information reported in the literature, however, on the actual length of its lifespan (Dzika, 2002; Pasternak et al., 2000). Argulus foliaceus is often noted for its role in ecosystems as an ecto-parasite. With a low host specificity, it has been found on almost every type of freshwater fish within its natural habitat, yet some fish are more susceptible than others. Argulus foliaceus has been reported on fish in the families Cyprinidae, Salmonidae, Gobiidae, Gasterosteidae and Acipenseridae as well as amphibians, including frogs and toads (Anura). In fish farms of Central Finland, it was found to coexist with Argulus coregoni, a closely related ecto-parasite. In addition to its function in ecosystems as a parasite, A. foliaceus can also be a vector for bacteria and flagellates and it serves as an intermediate host of nematodes in the family Skrjabillanidae (Oktener et al., 2006; Pasternak et al., 2004; Walker et al., 2007).

Lernaea cyprinacea has been recorded in many places around the world. It has been found in parts of Europe such as Scandinavia, France, Italy and Germany all the way to Japan. The parasite is spread throughout Central Asia as well as in the southern regions of West Siberia. The spread of Lernaea cyprinacea northward is limited by temperature. It is an exceptionally thermophilic organism

9 of southern origin and it develops successfully only at high temperatures. Tem- peratures between 23-30°C are the most favorable for development (Baur, 1962).

Many kinds of fish are the intermediate and definitive hosts. Mainly these hosts are from the family Cyprinidae. Fish such as Carissus auratus, Anguilla japonica, Carassius carassius, Gobio cynocephalus and Cypinus carpio, all are parasitized by Lernaea cyprinacea. Many fish serve as intermediate as well as definitive hosts during heavy infestation. The parasite feeds on the internal tissues of the fish. It attaches to the gill chambers of the fish and parasitizes it externally. This parasite is a big threat because it lacks host specificity to such an extent that it can infect all freshwater fish and even frog tadpoles and salamanders (Baur, 1962; Hoffman, 1967).

“Like all animals, fishes have their full compliment of disease and parasites and of disorders, both malignant and benign and there is no question that most fishes die from such disorders, natural enemies other than men”(Lagler, 1956). Helminth parasites generally affect the internal organs of the host fish, particularly the gut, they can perforate the intestine heavily and inhibit host’s growth. The normal growth of fishes is interrupted and inhibited if they are heavily infested with endoparasite viz., trematodes, nematodes, cestodes and acanthocephalans. These fish parasites like those of other vertebrates, feed either on the digested contents of the host’s intestine or the host’s own tissue (Markov, 1946). The irritating activities and damage of tissues lining the walls of the esophagus, stomach, intestine etc. cause microscopic lesions in their host’s tissues which become the site for the secondary infection by bacteria (Cheng, 1964). Each true fish parasite therefore uses the fish for its home and food and the total damage is related to the numbers of parasites present (Soulsby, 1968; Hoffman, 1970; Olsen, 1974).

The fish parasites either may be external or internal. The endo parasite infest usually internal organ of fishes. If the parasites are in the digestive tract, they feed either on the digested contents of the host’s intestine or the host’s tissues. The influence of the parasite may result in extensive change in individual organs or tissue or it can exert a general effect.

Study of parasites is very modern and recent in Bangladesh. Parasitic fish helminthes are not human parasites, except a few (Isoparorchis hypselobagri and Gnathostoma spinigerum) and therefore are not directly concerned with human nutrition. But the helminths by their damaging activities can suppress the fish growth and in severe cases can kill them thus may cause great loss to the fish stock, which are the major sources of animal protein (87%) to our people (Mannan, 1977). The helminth fauna of this continent including Burma and Ceylon was first studied by Southwell (1913 and 1930) and then by Baylis (1923 and 1939). Later on Srivastava (1936), Gupta (1951, 1953 and 1961), Gupta and Sharma (1976) published a series of papers on fish helminths.

In Bangladesh, Bashirullah (1972a, 1972b and 1974), Bashirullah et al. (1970, 1973), Khan and Yaseen (1969), Rahman (1968, 1971), Rahman and Ali (1966), Hafizuddin and Khan (1975) have taken some attempts to explore the parasitic fauna of the fishes of this region. These scientists worked mainly on the taxonomic aspects of the fish helminth of Bangladesh. Ahmed and Sanaullah (1976, 1977, 1978, 1979), Ahmed and Begum (1978) and Ahmed and Rahman (1976) have worked on the distribution of some aspects of biology of some metazoan parasites of fresh water and marine fishes. Beside Akhtar et al. (1989, 1990), Zaman and Khanum (1990), Chandra (1984, 1985) continued work in this field.

In India, minor attempt have been made by Gupta (1959, 1961) to study the parasitic fauna of fishes and published a series of research reports on the occurrence, prevalence, infestation (intensification) and index of infestation of parasitic fauna of freshwater fish. Ali (1968) worked on metazoan parasites in general and helminth parasites in particular of the vertebrates of Bangladesh. He recorded a few metazoan parasites in the East Pakistan, now Bangladesh.

Kakaji (1968) studied on helminth parasites of India fishes. In part I, he described the origin of Pleurogenes attui n. sp. and Azygia angusticauda. He collected P. attui from the intestine of Wallagonia attu, A. angusticauda from stomach of Mastacembelus puctatus, W. attu, Ophicephalus puctatus and P. marulius. He also described 12 sp. of trematodes parasites of Indian fishes. Among the seven new species identified, Bucephalus octotentacularia from W. attu was found.

Elahi (1969) studied on some endoparasites of fresh water fishes of the family Channidae of Dacca. He described Crowcrocaecum pakistanesis from the intestine of Channa marulias. Isoparorchis hypselobagri from the muscle, body cavity and swim bladder of Channa marulias and Channa striatus; Procamallanus daccai, Spirocamallanus sp., Gnatostoma sp. from the intestine of C. marulias and C. striatus; Pallisentis nagpurensis from the intestine of C. striatus.

Devaraj and Ranganathan (1971) worked on the incidence of I. hypselobagri among the catfishes of Bhavanisager reservoir. They recovered the worm from the air bladder of W. attu, in the viscera and body musculature of Callichrous bimaculatus and ovary of Mystus aor. They mentioned that I. hypselobagri utilizes W. attu as its final host and the intensity of the trematode increase with the host’s age.

Bashirullah (1972 a, 1972 b) investigated the distribution and occurrence of I. hypselobagri in different hosts and localities. Out of 25 hosts, he recorded seven new hosts from Dhaka, Bangladesh. He collected I. hypselobagri from swim bladder of W. attu, Mystus aor, M. cavassius, Channa punctatus and Nandus nandus. He found juvenile Isoparorchis in the lateral muscles of fishes within heavily pigmented cysts. He believed that the parasite actively penetrate the gut wall and migrate into the swim bladder of silurid fish. He also studied on the occurrence of G. spinigerum in the vertebrates of Bangladesh.

Bashirullah (1973) carried out a brief survey of the helminth fauna of certain marine and freshwater fishes of Bangladesh including W. attu, Rita rita, Notopterus notopterus, Puntius sarana, P. sophore, Clupisome sp., Glosogobius giuris, Channa sp., Heteropneustes fossilis, C. fasciatus, Xenentodon cancila, Nandus nandus and Mystus sp. He observed Cosmoxynemoids sp. from C. fasciatus and Pallisentis nandai from Nandus nandus.

Bashirulllah (1973) carried out a brief survey of the helminth fauna of Bangladesh. He prepared a list of the trematode, nematode and acanthocephalan parasites of some marine and fresh water fishes of Bangladesh. The total 92 taxa of parasites were listed from 49 taxa of fishes. No parasites were found in two marine and two fresh water fishes.

Anderson (1976) who worked on seasonal variation in the population dynamics of Caryophyllaeus luticeps. Dobson (1985) studied the competition between the parasites. Thomas (1964) worked on the population dynamics of digenetic trematode in vertebrates. Kennedy (1978) and Lawrence (1970) worked on availability of food and feeding activity, distribution and environment of host, which are influence the parasitic development. The parasites causes depletion of the nutritional contents in host’s body and results in the low productivity, loss in fish industry (Hiware, 1999).

Mustafa and Ahmed (1979) worked on Notopterus notopterus from pond and jheel water and found that this species was predominantly carnivorous and a column feeder. Protozoan, crystaceans and plants occurred in fish stomach in pond water and in jheel water. Insects occurred more in the jheel water fish compared to pond water fish. They also reported that N. notopterus was a column feeder in feeding habit consuming protozoan, crustaceans, algae, insects etc.

Mustafa et. al. (1981) studied the seasonal patterns of feeding of the fresh water fish Colisa fasciatus and showed that the fish prefers algae in winter, insect larvae in summer, diatoms and protozoan in autumn. He also observed that a high percentage of crustaceans were consumed by the fish in winter, spring and early summer months.

Zaman and Seng (1986) found the caryophyllid cestode, Djombangia penetrans infecting catfish Clarias batrachus and Clarias macrocephalus in Kedah, Malaysia. At the point of penetration, the epithelium was completely destroyed. Connective tissue, which originated from the sub mucosa layer surround the scolex. In heavy infection, the affected intestine enlarged, dilated and at the point of attachment, appears as a white dot.

Zaman et al. (1986) observed the effect of length (=age) of Clarias batrachus and Clarias macrocephalus, on the abundance of parasites from Khedah and Perak of Malaysia. Among 22 collected species only 12 were common in both fish. The numbers of the parasites increased with age and then declined in the largest size group.

Several parasitic diseases of fish and their possible remedial measures are important. Some histopathological evidence provides information for these fish diseases. Chowdhury et. al. (1986) studied the infestation of Isoparorchis hypselobagri in the swim bladder of Mystus vittatus, M. cavasius and M. tengra. Nahar (1988) investigated the prevalence and intensity of helminth parasites Xenentodon cancila and Benazir (1989) worked on the infestation of helminth parasites and some biological aspects of Mystus vittatus, M. cancila, M. cavasius and M. tengra.

No comprehensive survey has been carried out on the parasites of Wallago attu and Rita rita. No work has been done on histopathology of W. attu and Rita rita. Some mentionable work has been done in other parts of the sub-continent and some parasites have been identified through these works. Ventakeshappa et al. (1988) recorded a new host of W. attu of fish louse Ergasilus malnadensis in India. Gupta and Sharma (1982) found 17 new monogeneans Mizellus inglisi n. sp., from gill filaments of W. attu. Rajrswari and Kulkarni (1983) identified a new species Bychowskyella singhi from the gills of W. attu at Hydrabad, India. A rare gill monogenean Hamatopeduncularia lucknowensis n. sp. was identified by Agarwal and Sharma (1988) at Lucknow.

Gupta and Agarwal (1986); Symasunder et al. (1984); Gupta et al.(1983); Rao and Simha (1983) worked on various biochemical activity on Isoparorchis hypselobagri collected from the swim bladder of W. attu. Again Gupta and Parmar (1982) described Gangesia indica from the intestine of W. attu from Lukhnow. Duggal and Bedi (1987) recorded Opisthorchis pedicellata for the first time in W. attu. Several other parasites such as Allogomtiotrema gwaliorensis, A. attu, A. vidarbhasi sp. nov. etc. and also some other camallanid nematodes were discovered from this fish. The spawning season of the fish is from July to August. In other months they do not spawn. As soon as the rivers flood the streams and lakes they run up the shallow water for breeding. They build nests for breeding and offer parental care. So, this spawning is a suitable period for the fish to be infected.

In Bangladesh very few attempts have been made on the histopathological effects of parasites. Among the few, Ahmed and Sanaullah (1979), Ahmed and Rahman (1979), Zaman and Khanum (1990), Sultana et al. (1992) worked on Clarias batrachus, goldfish and

14 flatfish. Jahan (1971) thoroughly studied on the histology and histochemistry of I. hypselobagri. Very few studies have been done on parasitization, host parasite relationship and histopathology of I. hypselobagri. Siddique and Nizami (1978) reported incidents of these trematode from W. attu.

Devaraj and Ranganathan (1971), studied the incidents of these trematodes and its destructive effects on air bladder of W. attu, viscera and body musculature of Callichrous bimaculatus and ovary of Mystus aor. Mahajan et al. (1978) reported the effect of parasitization of juvenile I. hypselobagri in Channa punctatus. Rao et al. (1979) reported mature I. hypselobagri from Rana tigrina. Bhalerao (1932) gave a note on the probability of infection of man and domestic carnivores by this trematode. Verma and Ahluwalia (1980) and Shahadev and Simha (1980) reported similar unusual records and high survival index of I. hypselobagri, but none of them explained the pathology of these infections.

In Bangladesh, Islam (1970) indicated the overall prevalence of infestation of R. rita and parasites in the various organs, the sample size was small and he indicate monthly or seasonal variation of infestation or the distribution of parasites according to size and sex of the host. Sex and age of the host are important factors in the epidemiology of the parasites. The age or sex-prevalence and the age or sex-intensity can ascertain which sections of the community are most at risk. Therefore the present investigation was undertaken to determine the parasite fauna in R. rita according to season, sex and length of the host and also to note whether there has been any recruitment of parasites in the last 44 years.

Khanum et al. (1989) reported on the observation on helminth infection in relation to seasons and body lengths of Xenentedon cancila (Hamilton). Among the 4 length groups of the fish, the intermediate size-groups showed the highest prevalence of infestation. The intensity of the parasites maintained an inverse relationship with the length of the fish. Comparatively higher rate of infestation was observed in dry seasons.

Gupta and Masoodi (1990) worked on the Heptochona varmai (nematoda) of R. rita; De (1989) studied on the morphology of Cucullanus ritai (nematoda) from the intestine of R. rita; Singh and Jain (1988) described a new species Dogielius gussevi (monogenea) and

Gupta (1983) reported Bifurcohaptor hemlatae (monogenea) from the gill filaments of R. rita. Chowdhury (1992) studied on the helminth infestation and histopathological changes in snakehead fishes. She described cestode parasites Gangesia bengalensis from the intestine of Channa marulias; nematode parasites were Camallanus ophiocephali in the intestine of Channa striatus and Channa marulias and Spirocamallanus sp. In the intestine of Channa; acanthocephalan parasites were Pallisenis nandai in the intestine, stomach and body cavity of Channa striatus, Pallisentis nagpurensis was in the intestine of Channa marulias. All host fishes were collected from different fish markets of Dhaka city. In the histopathological study, he described that the intestine tissue was having damaged by the acanthocephalan parasites. The liver was damaged by pleurocercoid stages of cestode parasites. Muscle tissue were damaged by encyst at trematode parasites slight abnormalities were also observed in the stomach wall due to adult trematodes.

Wallago attu is one of the large freshwater catfish found in Pakistan, India, Sri Lanka, Nepal, Bangladesh, Burma, Thailand, Vietnam, Kampuchea, Malay Peninsula, Afghanistan, Sumatra and Java (Talwar and Jhingran, 1991; Giri et al., 2002). The rapid growth (Goswami and Devraj, 1992) and high nutritional quality of its flesh (Lilabati and Viswanath, 1996) encourage investigation into the aquaculture potential of this excellent food fish. Taking into consideration the various health risks, fish’s mineral and body composition and their health status were assessed in order to establish the safety level of the table sized species prior consumption (Fawole et al., 2007). Body composition illustrates the nutritional quality of food because analysis of biochemical composition including protein, fat and ash is very important in assessing food value (Kamal et al., 2007). So, biochemical evaluation is necessary to ensure the nutritional value as well as eating quality fish (Azam et al., 2004). However, the value of these body constituents vary significantly from one species and one individual fish to another depending on age, sex, feeding season, sampling time, activity and environmental condition (Weatherley and Gill, 1987; Jobling, 1994; Tang et al., 2009).

Khanum and Farhana (2002 a) studied on the parasitic infestation of the fish Wallago attu (Siluridae: Cypriniformes). Out of 59 specimens, 54 W. attu were infected by 788 parasites and the overall prevalence was 90.78% and the intensity of parasite infestation in

16 infected fish was 13.33. Khanum et al. (2008 a) investigated the community of helminth parasites in Rita rita (Hamilton Buchanun). They found three species of trematodes Phyllodistomum folium, Opisthorchis gomtii and Horatrema pristipomatis; one nematode Cucullanus dogieli; and larval form of pseudophyllidae cestode. Prevalence of infestation of P. folium and O. gomtii were similar (26%), but the intensity was higher (2.2) in case of P. folium. Lowest prevalence (9%) and lowest intensity (1.33) showed by H. pristipomatis. Infestation rate of C. dogieli was 10% and the intensity was 1.5. The prevalence of cestode larvae was found 13% and the intensity was 1.53.

Biochemical composition of fish shows very wide variation from one species to another within the same species in different portions of the body, from season to season, according to age, size, growth etc. The important constituents of the fish in their order of magnitude are moisture, protein, fat and minerals. Flesh from healthy fish contains 60 – 84% water, 15- 24% protein and 0.1 -2% fat. The proportions of constituents are species specific and main variation seen in fat content. Lean fish have less than 0.5% fat and fatty fish have more than 2% fat (Haque, 1975)

Global warming scenarios combined with political and public awareness have led to increasing funding and research efforts on the measurement and prediction of effects of a changing world on the ecosystems. Fish parasites represent a major part of aquatic biodiversity, and consequently become affected either directly through the environment or indirectly through their respective hosts. On the basis of a conservative estimate of an average of 3–4 fish parasites in each existing fish species alone and a current number of 31,400 described fish species, we can estimate the existence of up to 120,000 fish parasite species, including both protozoans and metazoans. Combined with a number of life cycle

17 stages that may infect all aquatic hosts and organs, this vast biodiversity represents a widely neglected tool for a variety of ecology-based applications.

Studies have demonstrated that fish parasites can serve as biological indicator organisms to illustrate the ecology of their infected hosts, including feeding, migration and population structure. Parasite metrics have been connected to specific environmental conditions, and they can indicate different pollutants such as heavy metal concentrations, industrial and sewage pollution, and also eutrophication. Most recently, parasite infections have been connected to anthropogenic impact and environmental change also in marine habitats.

Aquatic ecosystems along the costal zones belong to the most vulnerable systems on earth and face increasing anthropogenic stress in terms of pollution and environmental degradation. About 2.75 bn people are expected to live within 60 mi of the coastline in 2025, living from or indirectly using the coastal environments. This, however, is the region that harbours the highest aquatic biodiversity, especially in tropical coastal waters. It is obvious that extensive anthropogenic activities directly affect the species composition and diversity of the aquatic biota, possibly negatively influencing the long-term perspectives and sustainability of these ecosystems.

Fish parasite biodiversity and species composition in the aquatic realm depends on species richness of the final hosts and their ecosystem. The global fish fauna comprises more than 31,400 species (Froese and Pauly 2010), about half of them (14,970 species) live in marine waters. Because of the long-term stability of marine ecosystems, fish parasite diversity per host is higher than in freshwater. Rohde (2002) estimated 100,000 fish parasites in about 30,000 known fish species, resulting in an average of 3.3 parasite species in each fish studied. Margolis and Arthur (1979) and McDonald and Margolis (1995) recorded 925 different fish parasites on 292 marine and freshwater fish species from Canadian waters, including protozoans and metazoans (3.2 parasite species/fish species). Palm and Dobberstein (1999) reported 191 different metazoan parasite species from another northern habitat, the coastal waters of Germany. A total of 62 wild fish species from the North and Baltic Sea coast harboured an average of 3.1 metazoan parasite species per fish species. This contrasts the deep-sea, where the average number of parasites per fish species is 1.5, a value that did not

18 increase in the last 8 years (Klimpel et. al. 2001, 2009). On the basis of the existence of more than three metazoan fish parasites in each existing fish species alone, we can estimate the existence of up to 120,000 fish parasite species, including both protozoans and metazoans.

One of the most immediate and obvious effects of global warming is the increase in temperatures around the world. The average global temperature has increased by about 1.4 degrees Fahrenheit (0.8 degrees Celsius) over the past 100 years, according to the National Oceanic and Atmospheric Administration (NOAA).

Since recordkeeping began in 1895, the hottest year on record for the 48 contiguous U.S. states was 2012. Worldwide, 2012 was also the 10th-warmest year on record, according to NOAA. And nine of the warmest years on record have occurred since 2000. According to NOAA, 2013 tied with 2003 as the fourth warmest year globally since 1880.

Climate change has both direct and indirect impacts on fish stocks that are exploited commercially. Direct effects act on physiology and behavior and alter growth, development, reproductive capacity, mortality, and distribution. Indirect effects alter the productivity, structure, and composition of the ecosystems on which fish depend for food and shelter.

Brander et al. (2003), ICES (2006) and Drinkwater (2005) recorded that the effects of increasing temperature on marine and freshwater ecosystems are already evident, with rapid poleward shifts in distributions of fish and plankton in regions such as the North East Atlantic, where temperature change has been rapid. Further changes in distribution and productivity are expected due to continuing warming and freshening of the Arctic (Arctic Council 2005). Some of the changes are expected to have positive consequences for fish production (Brander and Mohn 2004), but in other cases reproductive capacity is reduced and stocks become vulnerable to levels of fishing that had previously been sustainable (Friedland et al. 2003). Local extinctions are occurring at the edges of current ranges, particularly in freshwater and diadromous species such as salmon and sturgeon (Reynolds et al. 2005).

A trend analysis over Dhaka city during the last 67 years (1953-2009) shows a decreasing trend of about 0.0154 mm per year. But the trend of the last 30 years (1979-2009) is found to

19 be increasing at a rate of 2.7 mm per year. Interestingly, ignoring the rainfall data of last ten years shows a decreasing trend of 1.06 mm per year. Records show that the more extreme events occurred over the last five years. The rainfall intensity of greater than 100mm is more frequent than rainfall intensity of greater than 125 mm. Although the rainfall intensity of greater than 150mm occurs infrequently but data from Bangladesh Meteorological Department (BMD) of last five years shows that the severity of this type of rainfalls increases. The mean daily predicted rainfall over the Dhaka city using PRECIS Regional Climate Model from 1951 to 2100 and observed by the station from 1953 to 2009. The trend of predicted rainfall is found increasing at a rate of 0.014mm per year whereas the observed rainfall also shows an increasing trend of 0.0103mm per year. The trend of predicted monsoon rainfall is about 0.1214mm per year and that of observed monsoon rainfall is 0.0033mm per year. It has been found that extreme rainfall events over the Dhaka city have increased over the last decade. Both regional climate model and observed data show increasing trends of rainfall. Hence, the climate change will impact the extreme rainfall events of the city.

Bangladesh’s unique geographic location, with the Indian Ocean to the south, the Himalayas to the North and the prevailing monsoons, has made it one of the wettest countries of the world. The mean annual rainfall is about 2320mm, but there are places with a mean annual rainfall of 6000mm or more (Hossain et al., 1987). A long duration of heavy rainfall associated with “norwester” thunder storms is very common in Bangladesh (Hossain et al., 1987, Rafiuddin et al., 2009). In September 2004, 341mm rainfall occurred in 8 hours in Dhaka which led to severe urban flooding (Ahmed, 2008). Serious drainage congestion took place in Dhaka city due to 333mm rainfall on 28th July, 2009 (Uddin, 2009). On that day around 290mm rainfall occurred in six hours. On 11 June, 2007 around 408 mm rainfall was measured in Chittagong that resulted in landslide killing at least 124 people (Uddin, 2009).

According to the fourth assessment report of IPCC the mean temperature of the earth has been increasing at a rate of 0.74 degree centigrade per century (IPCC, 2007). It is also found that climate change has profound impact on rainfall intensity and variability (Wasimi, 2009). Global Climate Models showed that global warming will increase the intensity of extreme precipitation events (Allan and Soden, 2008). Regional projections also revealed that climate

20 changes would strengthen monsoon circulation, increase surface temperature, and increase the magnitude and frequency of extreme rainfall events. Regional climate models predict a large increase in annual precipitation although the more recent PRECIS run showed that the dry season is becoming drier and water deficit is increasing due to population growth (Fung et al., 2006). Therefore, climate change will certainly bring changes to rainfall pattern. Rainfall pattern will change due to global warming although the exact degree of change is not yet determined. This change will affect fresh water supplies that have already been stressed due to rising population and increased per capita consumption. This will cause more difficulty in estimating extreme rainfall events since there will no longer be a homogeneous series of values which can be extrapolated statistically. However, it is expected that higher extreme events will occur than before (Linarce, 1992).

Sunlight also affects temperature, and humidity is dependent on temperature. Temperature and humidity greatly influence the lives of organisms. When living things get too hot or too cold, their bodies do not function properly. Processes such as digestion, respiration, excretion and reproduction take place at an optimum (most favourable) temperature range. That is why many desert creatures sleep during the extremely hot days and emerge in the cool of the night to feed and engage in courtship.

Humidity is the amount of water vapour in the air. The humidity of the air will determine the amount of water an organism loses into the air. In areas where there is high humidity such as in tropical biomes, organisms will lose very little water. Desert biomes, however, have very little humidity and so plants and animals living in these areas will have special adaptations that help them to retain as much water as possible.

While humidity itself is a climate variable, it also interacts strongly with other climate variables. The humidity is affected by winds and by rainfall. At the same time, humidity affects the energy budget and thereby influences temperatures in two major ways. First, water vapor in the atmosphere contains "latent" energy. During transpiration or evaporation, this latent heat is removed from surface liquid, cooling the earth's surface. This is the biggest non- radiative cooling effect at the surface. It compensates for roughly 70% of the average net radiative warming at the surface.

Second, water vapor is the most abundant of all greenhouse gases. Water vapor, like a green lens that allows green light to pass through it but absorbs red light, is a "selective absorber". Along with other greenhouse gases, water vapor is transparent to most solar energy, as you can literally see. But it absorbs the infrared energy emitted (radiated) upward by the earth's surface, which is the reason that humid areas experience very little nocturnal cooling but dry desert regions cool considerably at night. This selective absorption causes the greenhouse effect. It raises the surface temperature substantially above its theoretical radiative equilibrium temperature with the sun, and water vapor is the cause of more of this warming than any other greenhouse gas. Unlike most other greenhouse gases, however, water is not merely below its boiling point in all regions of the Earth, but below its freezing point at many altitudes. As a condensable greenhouse gas, it precipitates, with a much lower scale height and shorter atmospheric lifetime- weeks instead of decades (Wikipedia, the free encyclopedia).

The most humid cities on earth are generally located closer to the equator, near coastal regions. Cities in South and Southeast Asia are among the most humid. Kuala Lumpur, Jakarta, and Singapore have very high humidity all year round because of their proximity to water bodies and the equator and often overcast weather. Some places experience extreme humidity during their rainy seasons combined with warmth giving the feel of a lukewarm sauna, such as Kolkata, Chennai and Cochin in India, and Lahore in Pakistan. Sukkur city located on the Indus River in Pakistan has some of the highest and most uncomfortable dew point in the country frequently exceeding 30 °C (86 °F) in the Monsoon season. High temperatures couple up with bizarre dew point to create heat index in excess of 65 °C (149 °F). Darwin, Australia experiences an extremely humid wet season from December to April. Shanghai and Hong Kong in China also have an extreme humid period in their summer months. During the South-west and North-east Monsoon seasons (respectively, late May to September and November to March), expect heavy rains and a relatively high humidity post- rainfall. Outside the monsoon seasons, humidity is high (in comparison to countries North of the Equator), but completely sunny days abound. In cooler places such as Northern Tasmania, Australia, high humidity is experienced all year due to the ocean between mainland Australia and Tasmania. In the summer the hot dry air is absorbed by this ocean and the temperature rarely climbs above 35 °C (95 °F).

Justification of the work:

As there is no detail record of parasitological, histo-pathological and biochemical works on Wallago attu and Rita rita; so, the present investigation has been under taken to investigate the detail information regarding the parasitological aspects of Wallago attu and Rita rita .

The catfish W. attu have been chosen for investigating the helminth parasites for the human welfare. Considering all these above mentioned fragmented studies done on W. attu and R. rita, also to increase the production of this fish in the country primarily by culture, their nutritional status and parasitic information were necessary. As no systematic study of the parasite of Wallago attu and Rita rita has been done in our country, it was aimed to study the different aspects of parasitic infestation and infection of the fish.

So the aim and objectives of this study are:

 To investigate the diversity of ecto-parasite (arthropods) and endo-parasite (helminthes) community of Wallago attu and Rita rita.  Find out the distribution pattern of different types of parasite in different parts and organs of the host fishes.  Find out the relationship of incidence and occurrence of parasite infestations with their length and sex of fish.  To determine the relationship between the parasitic infection in Wallago attu and Rita rita in different months and seasons.  Determine the seasonal variation in prevalence and intensity of the parasite infestation within the host fishes.  Find out the histo-pathological effects on host fishes due to parasitic infestation.  Determine the variation in biochemical components like protein, carbohydrates, fat, ash, moisture in infected and non-infected Wallago attu and Rita rita.

CHAPTER – 2

REVIEW OF LITERATURES

The purposes of review of literatures were to collect the information regarding the background, history and previous relevant studies. A remarkable number of national and international literatures were cited and reviewed which were closely related to the present study. The summarized information’s / literatures are given below:

Food and feeding habits of fishes:

Moffett and Hunt (1943) worked on the winter feeding habit of the blue-gills. They noted a change in food habit of this fish with the change in season and recorded little food in the stomach in winter.

Mookherjee et. al. (1946) worked on Glossogobius guiris and reported that animals and plants occurred in the ratio of 70:30 in the adults, but the ratio of plant materials was more in the juveniles.

Angelouplu (1947), Hossain (1997), Bolock and Koura (1959) stated that Clarias gariepinus is a carnivore fish, because of a small gut, body length ratio in comparison with other species and because it lacked pyloric caeca.

Mookerjee and Mazumder (1950) studied some aspects of life history of Clarias batrachus and found that fry of this fish takes protozoan, small crustaceans, algae, worms, rotifers etc. as food and the adult fish takes insect larvae, fish, shrimps, worms, algae and other vegetable debris.

Pillay (1952) stated that the correct picture of the food and feeding habit of a fish might not be obtained by the examination of the gut contents of a few specimens at random. But an extensive study of the gut contents spread over the various seasons of the year could yield information of value for fishery development and management.

Karekar and Bal (1958) correlated the feeding intensity with the maturity stages of fish. They observed that the feeding intensity of the fish slowed down with the growing maturity stages. Particularly in females the feeding was considerably reduced when the fish reached the final stages of maturity and rose again after spawning is over.

Nikolosky (1963) reported that in most cases fish did not show any considerable variation in their diet, except feeding intensity which differs due to their spawning season. He also recognized three categories of food on the basis of their importance in the diets of fishes.

Ahmed et.al. (1980) worked on the food and feeding habits of the catfish, Clarias batrachus and found that the food of adults and juveniles varied considerably, the adults consumed mainly chironomid larvae, copepods etc. while the juveniles consumed mainly chironomid larvae, ostracods and dragon flies.

Siva and Rao (1983) did a detail observation on the food materials of 354 Mystus vittatus collected from Hussain Sagar lake and concluded that M. vittatus feed mainly on insect larvae (35.3%) and insects (16.3%) found there. The other food items include both plant and animal matter.

Ali et al. (1985) worked on the food and feeding habits of P. pangasius and stated that, this fish is fairly an omnivore and among their food macro-crustaceans occupied the highest position. Their investigation also reveals that P. pangasius does not complete with the plankton feeders and concluded that P. pangasius can be cultured in pond with major carp.

Kader et al. (1988) worked on the food and feeding habits of Gobioides rubicundus and observed that the main foods were shrimps, crabs, gobioid juveniles, chaetognaths, copepods and occasional items were algae and diatoms. He also reported that the number of mature male fish with empty stomach was highest in the prespawning month while female was highest empty stomach during the spawning month.

Fish Biology:

Kulasiri and Fernando (1956) recorded Camallanus anabantis in Anabas testudineus, Ophicephalus punctatus, Puntius filamentus and Rasbora daniconius. P. filamentus, R. daniconius and O. punctatus are new hosts for this spp. P. planoratus was recorded in Clarias batrachus and Clarias spp. They also recorded C. sweeti in A. testudineus, C. batrachus and Clarias spp.

Clay (1979) observed sexual maturity and fecundity of the African catfish (Clarias gariepinus) with observation of the spawning behavior of the Nile catfish (Clarias lazera).

Hine (1980) worked on the nematode parasites and found both male and female Spirocamallanus species established in the mid intestine. Parasites most often found in the mid intestine, but occurred throughout the intestine. He also noticed that the larger worms moved and were lost more rapidly than smaller worms.

Fish Parasitology:

Bhalerao (1932) wrote a note on the probability of infection of I. hypselobagri (Billet,1898) in man and domestic carnivores. He listed the occurrence of I. hypselobagri from gas bladder of W. attu. He also obtained immature forms of this parasite from muscle lining the coelomic cavity of Ophocephalus striatus.

Gupta (1961) described 3 new genera and 1 new species of the family caryophyllaeidae (Leuckart, 1910) from the intestine of Heteropneustes fossilis from U.P and Assam.

Baur (1962) reported Lernaea cyprinacea can obviously become a problem for fish farmers. The parasite not only causes disfigurment in the fish, but it can also cause its death in cases of high infestation. The farmers are unable to sell these sick fish and lose a great amount of money. In Japan, the parasite has increased its number and spread to such an extent that it is a serious menace to fishing

26 culture. It was first found to be causing damage to eels, in this case choking the mouth cavity, but it is also found on other fish, burrowing with the head under the scales. Countless pounds of fish have been destroyed because of this parasite.

Furtado (1963) obtained a new species of the family Caryophyllaeidae, genus Lytocestus parvulus sp. from the intestine of the Malayan freshwater siluroid, Clarias batrachus (L.). About two hundred specimens were collected from the intestine of three C. batrachus. A general but brief account of this helminth was incorporated in the paper.

Fischthal and Robert (1963) redescribed digenetic trematode of fishes from Egypt. He collected Orientocreadium batrachoides Tubangui, 1931 (Plagiorchioidea) from Clarias lazera with some morphological variations. They reviewed the morphological differences and similarity of the hosts of the species of Orientocreadium and their related forms.

In 1969, Tedla and Fermando observed that the seasonal changes in incidence and intensity of infestation of Perca flavescens, by eight species of adult and larval parasites. The incidence of ectoparasite, Ergasilus confuses, reached its peak of incidence in the summer and declined in winter.

In Bangladesh Rita rita has been known to be infected by helminth parasites (Islam, 1970). He first studied the helminth parasites of R. rita from Sunamganj and identified 4 helminth parasites i. e. Opisthorchis sp., Phyllodistomum yosufzai, Cucullanellus sp. and some larval nematodes. But his sample size was only eight fishes. Therefore, the parasites of this fish need to be investigated in a more detailed manner.

Datta (1971) studied on the digenetic trematodes and nematodes of some fresh water fishes of Dacca. He described Camallanus adamsia from the intestine of Barbus saphora (Ham.) and Spirocamallanus olsenia from the intestine of Mystus vittatus (Bloch).

Rehana et al. (1972, 1974, 1979) described three new species of genus Procamallanus, P. wallagus, P. kalriai, P. karachii from the swim bladder of W. attu of lake kalri, Sind, Pakistan and also reported the infestation of P. wallagus from Mastacembelus puctatus.

Furtado and Tan (1973) have surveyed the parasite fauna of Clarias batrachus in the paddy fields of Sungei Besar and Sabak Bernam in Selangor. They provided some information on the seasonality of four species of parasites, namely two cestodes: Lytocestus lativitellarium, L. parvulus and two nematodes Procamallanus clarias and P. parvulus.

Devi (1973) collected Lytocestus longicollis sp. nov. (Cestodea: Caryophyllidea) from the catfish Clarias batrachus (L.), a fresh water siluroid, common in the Indo-Malaysian region. She discussed and compared the morphological descriptions of Lytocestus longicollis and L. indicus.

Srivastava and Mukherjee (1974) studied the incidence of infestation of I. hypselobagri metacercaria in two species of fishes of the genus Mystus; M. aor and M. seenghala. They found the encysted metacercaria in the coelomic muscles and body cavity of these fishes.

Ahmed and Sanaullah (1976) observed the incidence and intensity of infestation of some helminth parasites of different length groups of Heteropneustes fossilis (Bloch) and Clarias batrachus (Linnaeus) in Bangladesh.

Ahmed and Sanaullah (1977) studied on the distribution on some metazoan parasites of two specimens from six different regions in the districts of Bogra, Dhaka, Mymensing, Noakhali, Rangpur and Sylet in Bangladesh and collected 14 metazoan parasites.

Ashrafuddin (1977) studied on some helminth parasites from five species of commercially valuable fishes of the Bay of Bengal. He described Spirocamallanus sp. from the intestine of Sardinella frimbiata and Dussumicria acuta.

Ahmed and Sanaullah (1977) reported Procamallanus Bangladeshi, P. bengalensis, Gnathostoma spinigerum, Spirocamallanus olsenia and a quimperid larva from H. fossilis.

Mahajan et.al. (1978) reported the widespread infestation by fully developed sexually adult state of I. hypselobagri in Channa punctatus, a non-siluroid fish. In a single fish usually 2-5 adult parasite with a no. of juveniles showed exceptional variation in number and size and the degree of infestation was very high.

Wabuke and Bunoti (1980) worked on the prevalence and the pathology of the cestode Polyonchobothrium clarias (Woodland, 1925) in the teleost, Clarias mossambicus (Peters).

Shotter (1980) described the parasitology of the cat fish Clarias anguillaris (L.) from a river and a lake at Zaria, Kaduna State, Nigeria. The parasite fauna of C. anguillaris from lake Samara and the river Galma in the northern Savannah region of Nigeria was represented by Henneguya sp., Macrogyrodatylus classi trematode species and 2 each of cestodes, nematodes and copepods.

Mackiewicz (1982) synoptically reviewed the Caryophyllidea (Cestoda) of India, Pakistan and Nepal . He studied the biology and systematics of the approximately 18 species of caryophyllid cestodes from India, Pakistan and Nepal. He reported that the dominant hosts are siluriform and cypriniform; Clarias batrachus and Heteropneustes fossilis were the chief hosts.

Gupta et.al. (1983) comparatively studies on non-specific phosphomonoesterases, glucogen and pyruvic acid in I. hypselobagri from the air bladder and body cavity of W. attu.

In India, Ahmad (1984) described Styapalia guptai (digenea); Agarwal and Agarwal (1984) – Oudhia kanungoi (digenea); Bhadauria and Dandotia (1984) – Pleurogenoides ritai (trematoda); Agarwal and Sharma (1989) – Nicolla fotedari (trematoda) and Maurya and Agarwal (1989) also described Masenia chauphani (digenea) from the fish Rita rita. In Pakistan, Khan (1985) described a new species Phyllodistomum ritai (trematoda) from the urinary bladder of R. rita.

Ahmed et al. (1985) investigated the organal distribution of some caryophylid cestode parasites and their seasonal fluctuation in the gut of Clarias batrachus and Heteropneustes fossilis from Dhaka, Bangladesh. They reported that the parasites showed higher abundance in summer and rainy season.

Many works have been done on the morphology of the helminth parasites of R. rita in India and Pakistan. Gupta and Govind (1985) described Haplorchoides kherai (trematoda); Gupta and Singh (1983) described Pseudocaryophyllaeus ritai (caryophyllaeidae) from the intestine of R. rita in India.

Chowdhury et al. (1986) studied on the intensity of infestation and abundance of I. hypselobagri in the hosts Myatus vittatus, M. tengara and M. cavasius.

Gupta and Jaiswal (1986) collected Metaquimperia ophiocephali from the intestine of the fresh water fish Ophiocephalus marulius, Paracucullanellus thapari from the intestine of the freshwater fish W. attu.

Bhaduria and Dandotia (1986) described 10 new and 6 already known species, among them Bucephalus gwaliorensis, B. attuai, Opisthorchis attuai, O. pedicellate and Phyllodistomum spatulaeformae from W. attu.

Zaman and Leong (1987) worked on caryophyllid cestode in Malaysia and reported 37.7% prevalence of Lytocestus parvulus in Clarias batrachus with a mean intensity of 11.3. No seasonal cycles of prevalence and intensity or maturation of the cestode were detected. The abundance of the parasite decreased with increasing size of the host.

Duggal and Bedi (1987) worked on one new and 4 already known species and subspecies of Opisthorchis lanchard, 1895 and O. pedicellata pedicellata is described from mew hosts, Bagarius bagarius and W. attu and was found in the intestine for the first time.

Chakravarty and Tandon (1988) had done some histopathological observations of caryophylliasis in the cat fish Clarias batrachus and the status of caryophyllidea with a

30 report of some caryophyllid infections in the Clarias batrachus, in north-east India and a record of an anomalous form.

Sinha (1988) examined Clarias batrachus and found infection of Procamallanus spp. The average burden of Procamallanus spp. was found to be 2.65/ fish and there was no significant difference in the burden of male (1.62) and female (2.70) fish.

Venkateshappa et. al. (1988) has described a new parasitic copepod species Ergasilus malnadensis parasitizing W. attu. They again noticed the incidence and inetcsity of this parasite. Infestation on W. attu in Vanivilasa sagar reservoir, Karnataka. The incidences of infestation were 80 to 100 percent and 1 to 1,629 parasites/fish respectively.

Chakravarty and Tandon (1989) worked on histochemical studies on Lytocestus indicus and Djombangia penetrans, caryophyllidean cestode parasites of Clarias batrachus (L.).

Mashego and Saayman (1989) observed on the prevalence and intensity of some digenetic trematodes and some cestodes of Clarias gariepinus (Burchell, 1822) in Lebowa, South Africa, with taxonomic notes.

Akhtar et. al. (1989, 1990) observed the helminth infection in relation to seasons and body length of X. cancila. One acanthocephalan, 3 nematode sp. encysted ascaroid larvae, Metaquimpera bagarii and Camellaus gaboes were found available from X. cancila. They also found that the intermediate length groups were more infected than the smaller and larger size group. They discussed the incidence of helminth parasites in this fish in relation to food items.

Gupta and Naiyer (1990) described a new nematode Procamallanus guptai sp. nov. from the intestine of a fresh water fish Heteropneustes fossilis (Bloch) from Lucknow. This worm differed from all the known species of the genus Procamallanus except Procamallanus ahiri (in the presence of esophageal gland; in the number and arrangement of caudal papillae; last pair being “U” shaped; in the presence of phasmids near tip of male tail curved ventrally with well developed caudal alae).

Khanum et al. (1992) recorded the correlation of sizes of H. fossilis with the rate of helminth infection. They found that the first intermediate size group had the highest prevalence of infection and the second intermediate size group was associated with the highest intensity of helminthes.

Nahar (1993) reported a comparative study on incidence of endoparasites in relation to some biological aspects of Channa striatus and Channa marulius from Dhaka, Bangladesh. She described cestode parasites Bothriocephalus cuspidatus from the stomach, intestine and liver of Channa striatus and Channa marulius. Taphrobothrium Japanese was in the intestine of Channa striatus and Channa marulius, Polyoncobothrium spp. was in the intestine and stomach of Channa striatus and Channa marulius. Digenetic trematode was Allogomtio tremaatta from the stomach of Channa striatus; nematode parasite was Camallanus spp. in the intestine of Channa striatus and Channa marulius; acanthocephalan parasite was Pallisentis nagpurensis in the stomach and intestine of Channa striatus and Channa marulius.

Nahida (1993) observed the helminth parasites and histopathology of infested organs in N. nundus. She found 4 trematodes Coitocaecum orthorchis, Opegaster sp.,Podocotyle atomon, Halipegus sp. 2 nematodes, Gnathostoma spinigerum, Porrocaecum sp., 1 cestode, Bothriocephalus sp. and 1 acanthocephala, Pallisentis nandai from the host fish. She found that the female hosts were more infested than the male hosts. The prevalence and intensity was highest in summer and lowest in winter season. The largest group and weight group showed the highest prevalence and intensity.

Yasmin et al. (1994) worked on Identification, organal distribution, seasonal variation and correlation of prevalence and intensity of infestation of helminthes in Clarias batrachus.

Khanum and Parveen (1997) reported on the Organal distribution and seasonal prevalence of endoparasites in Macrognathus aculeatus (Smith) and Mastacembelus armatus (Day). The prevalence of infection was highest during the rainy season in Macrognathus

32 aculeatus, while in Mastacembelus armatus the prevalence was highest in the winter. In both the species, heavy infestations were recorded in the largest length groups.

Lyngdoh and Tandon (1998) studied on putative neurosecretory cells in the monozoic cestode, Lytocestus indicus (Caryophyllidea). In Lytocestus indicus putative neurosecretory cells (PNSC) are recognized on the basis of the nature of their cytoplasm. PNSC in Lytocestus indicus are dimensionally small. Morphologically, there are four types of PNSC: a-, uni-, bi- and multipolar cells.

Pasternak et al. (2000) studied on Argulus foliaceus usually copulates on the surface of a host fish, but copulation has also been observed on other types of solid surfaces such as leaves and stones. This is an obligate bloodsucker and it cannot survive more than few days without a host. Having little specificity for hosts, it infects a wide range of species.

Eduardo et al. (2001) examined catfish Clarias batrachus and mudfish (Ophicephalus striatus Bloch) from Laguna, Philippines for helminth parasites. The recovered parasites prevalence’s are as follows: from the catfish – Orientocreadum batrachoides (16%), Eumasenia sp. (24%), Oudhia sp. (34%), Lytocestus birmanicus (10%), Lytocestus lativitellarium (48%) and Procamallanus clarius (46%).

Chandra and Yasmin (2003) investigated Monogenetic trematodes in air-breathing Clarias batrachus, Heteropneustes fossilis, Colisa fasciata and Anabus testudineus. Three new species Heteronchocleidus colisai, H. bangladeshi and H. anabusi were described, along with previously recorded Bychowskyella tchangi, Quadricanthus kobiensis and Heteronchocleidus buschkiella. All these parasites were recovered for the first time in Bangladesh.

Alam (2006) did a study where helminth parasites found in Notopterus notopterus were examined. In total, 4 of parasites species were recorded in this study. These were one from nematoda and three from trematoda. One species of nematoda i.e. Spirocamallanus notopteri and two species of trematoda i.e. Phyllodistomum folium and Singhia thapari were found in

33 the intestine. Whereas, Ancylodiscoides notopterus, an only monogenea trematoda was collected from the gills of the host. It is believed that the later species is the first report from Bangladesh.

Khanum et al. (2006) worked on the infestation of ectoparasites in Gudusia chapra (Hamilton). Heavy infestations (100%) were recorded in male of the largest (14.25-17.0 cm) and the smallest (6.0-8.75 cm) length groups. Total infection rate was also higher in males (87.72%) than in females (83.82%). Intensity of infestation in males and females was 1.62 and 2.03 respectively.

Parveen and Silva (2006) reported seven species of helminth parasites of Anabas testudineus was collected among which three species were trematodes: Neopecoelina saharanpurensis, Ptychogonimus megastomus, Brevicreadium congeri and four species were nematodes: Zeylanema anabantis, Z. bidigitalis, Metaquimperia madhuai and Gnathostoma spinigerum. Most of the parasites were found in the intestine. Only G. spinigeru were collected from the liver. The overall prevalence of infection of the parasites of A. testudineus was 90% and the intensity was 3.33. The prevalence was higher (100%) in male fishes than in female fishes (84%). The intensity was equal in both the male and female fishes (3.33). The prevalence (90%) and intensity (2.78) of trematodes were highest among the parasite groups. Both the prevalence and intensity were highest in the intermediate length and weight groups of fishes.

Taylor et al. (2006) reported direct predation of free-swimming Argulus foliaceus by trout and some other fish species has been observed.

Parveen and Silva (2007) studied on 8 species of helminth parasites in Nandus nandus (Ham. Buch. 1822). Among them, 2 species were trematodes: Coitocaecum orthorchis and Clinostomum piscidium; 1 species and 1 genera of cestodes: Bothriocephalus cuspidauts and Diplopulidium sp.; 1 species and 2 genera of nematodes: Gnathostoma spinigerum, Contracaecum sp. and Porrocaecum sp., 1 species of acanthocephala: Pallisentis nandai were found in the intestine of host. The overall prevalence and intensity of infection was 55% and 3.72 respectively. The prevalence was higher (65.21%) in female than in male (41.17%)

34 fishes. Similarly, the intensity in the male and female fishes were 4.00 and 3.6 respectively. The highest number of host fish was infected by nematode parasites (45%) with the highest mean intensity 2.22. Among the parasites, Porrocaecum sp. had the highest prevalence (22.5%) and Clinostomum piscidium had the lowest prevalence. Fishes of intermediate length but highest weight group had highest prevalence of infection.

Khanum et al. (2008) reported the endohelminth infestation in Channa punctatus (Bloch, 1794). They found 46.7% were infected with 4 species of endohelminths such as Ancistrocephalaus microcephalus, Haplonema immulatum, Camallanus anabantis and Pallisentis ophiocephali. The infestation was higher in male (63.9%) than female (35.2%). Among the identified endohelminths, highest (33.3%) and lowest (3.3%) prevalence showed by P. ophiocephali and A. microcephalus, respectively.

Khanum and Yesmin (2010) worked on the parasite infestation in Clarias batrachus (Linnaeus) and Clarias gariepinus (Burchell). They found 16 species of parasites (ten cestodes: Djombangia penetrans, Pseudocaryophyllaeus indica, Capingentoides batrachii, Lytocestus parvulus, Lytocestus indicus, Marsipometra confusa, Stocksia pujehuni, Caryophyllaeus laticeps, Bothriocephalus scorpii and Bothriocephalus salvelini; three trematodes: Lissorchis fairporti, Holorchis legendrei and Allocreadium isoporum and three nematodes: Spirocamallanus olsenia, Procamallanus bengalensis, larva of Paraquimperia tenerrima) in C. batrachus while only four species found in C. gariepinus (two cestodes: Djombangia penetrans, Lytocestus parvulus; one trematode – Allocreadium isoporum and one nematode – Procamallanus bengalensis). The prevalence was 80.60% in C. batrachus and mean intensity was 13.74 ( SD ± 12.67) while in C. gariepinus, prevalence was 37.20% and intensity was 1.60 (SD ± 0.958).

Khanum et al. (2011) studied on seasonal prevalence, intensity and organal distribution of helminth parasites in Macrognathus aculeatus. They detected six species of helminths (two trematodes- Clinostomum piscidum, Rhynchooharynx paradoxa; one cestode-Marsipometra parva, three nematodes – Pseudoproleptus vestibules, Cucullanus cirratus and Porrocaecum trichiuri L3 larva). The prevalence and intensity of parasitic infection were a bit higher in female fish than in male. The parasites were much more abundant in rainy season (75%)

35 followed by summer (62.5%) and winter (31.81%). The larger fishes were heavily infected (71.01%) than medium (53.33%) and smaller (52.17%) fishes.

Farhana and Khanum (2013) reported the distribution of helminth parasites in different organs of Mystus aor (Hamilton) and Mystus bleekeri (Day). To investigate the helminth infestation and their organal distribution, a total of 1011 Mystus aor and 1039 Mystus bleekeri were examined during January 2004 to December 2005. In M. aor, the overall prevalence was 85.95% with a mean intensity of 46.26  12.0, whereas in M. bleekeri, 72.95% prevalence with mean intensity of 56.49  12.29 was recorded. Out of 22 species of helminth parasites from M. aor, 10 sp. of trematodes, 2 sp. of cestodes, 6 sp. of nematodes and 4 sp. of acanthocephala. From M. bleekeri, out of 18 species of helminth parasites, 8 sp. of trematodes, 1 sp. of cestode, 5 sp. of nematodes and 4 sp. of acanthocephala were recovered. In M. aor and M. bleekeri, two trematodes Masenia collata and Isoparorchis hypselobagri were found most prevalent and most numerically dominant. Macrolecithus gotoi was found only in M. aor. Procamallanus mysti, Pallisentis gaboes and Acanthosentis datti were more prevalent. Majority of the parasites harbored the intestine and some harbored the stomach and other visceral organs. Some larval forms of nematode and acanthocephala were found to infest the coelomic cavity and mesenteries of the two fishes. The juvenile or immature trematode Isoparorchis hypselobagri was recovered from body muscles, swim bladder and visceral organs of the fishes causing massive tissue damages in M. aor.

Histopathological aspects:

Among the workers who have undertaken histological research on tissues of various freshwater fishes are: Hunter (1928, 1930), Chauhan and Ramakrishnan (1958), Bauer (1959), William (1960), Bullock (1963), Kennedy and Walker (1969), Mackiewicz (1972), Esch and Huffines (1973), Hine and Kennedy (1974), Jain et al. (1976), Ahmed and Sanaullah (1979), Wabuke and Bunoti (1980), Mitchell et al. (1982), Khanum (1994), Khanum and Farhana (2002) etc.

Hunter and Hunter (1942) theorized that the black pigment of the interfacicular connective tissue of the host was mediated by an enzyme reaction, which caused mechanical obstruction due to the occurrence of parasite in clusters. Roberts et. al. (1986) pointed out that the internal organ of infected fish show only mild histopathological changes which may be the result of background pathology.

Helminths in fishes are also recognized as causing serious effect on their hosts (Dogiel, 1964; Sindermann, 1970; Ribelin and Migaki, 1975). Ozaki (1926) first described changes in the stomach of a fish host brought on by a trematode Genarchopsis sp. Woodland (1935) mentioned the condition of the intestine due to the presence of a cestode Gangesia sp. Changes brought on by nematodes have been noted by Yeh, 1960.

Very few studies have been done on parasitization, host-parasite relationship and histopathology of I. hypselobagri. Siddique and Nizami (1978) reported incidence of this trematode from W. attu. Deveraj and Ranganathan (1971) studied the incidence of this trematode and its destructive effects on air bladder of W. attu, viscera and body musculature of Callichrous bimaculatus and ovary of Mystus aor.

Ahmed and Sanaullah (1979) studied the comparative histopathology as related to modes of attachment and scolex morphology, gross anatomy, host response and effects of the three caryophyllid cestode, Djombangia penetrans, Lytocestus indicus and L. parvulus. Khanum (1994) observed severe pathogenic lesions done by juvenile I. hypselobagri on the skin surface, body musculature, liver, intestine, kidney and other visceral organs in two species of Ompok.

Khanum and Farhana (2002 b) studied on the histopathological effects of a trematode Isoparorchis hypselobagri (Billet) in Wallago attu (Bloch and Schneider). In this experiment both the encysted and free forms found in these organs caused damaged to muscle tissue and perforations in the liver. The juvenile form of I. hypselobagri disrupted the structural integrity of the body musculature and visceral organ of the host.

Naser and Mustafa (2006) studied the histoanatomical and histonumerical analysis of the digestive system of Channa punctatus. The digestive tract was short in length and the digestive system includes large mouth with sharp teeth, highly distensible oesophagus, a large stomach, a number of pyloric caecae and a short intestinal tract. The mucosal layer of the oesophagus is highly folded, the stomach was distinct with strong and branched villi and the intestine was short with long villi.

Yesmin and Khanum (2013) worked on Histo-pathological affects due to helminth infestation in Clarias batrachus (Linnaeus) and Clarias gariepinus (Burchell). Two catfish, Clarias batrachus (1000 ) and C. gariepinus (500 ) were examined throughout two years time period. Total sixteen parasites species were recovered from these two fishes. In the present observation, the liver, stomach and intestine were found to be infected by numerous nematode, cestode and trematode parasites. Serious pathogenicity was observed due to the infection of the cestodes in C. batrachus. Among the recovered sixteen parasites, the maximum damage were caused by Djombangia penetrans followed by Lytocestus parvulus, L. indicus, Capingentoides batrachii caused complete penetration through the stomach and the scolex was deeply buried up to the serosa layers caused shallow ulcers and lesions. While in C. gariepinus, no remarkable histopathological damages observed caused by the inhabiting parasites. Histozoic helminths, particularly migrating forms causes greater damage. In some cases, produced most serious reactions: leukocytosis, fibrosis, hemorrhage, hyperemia and necrosis. The caryophyllaeid cestodes inflict by their scolex, as they anchor to the wall of the stomach and intestine and causes shallow ulcers and lesions. Due to severe infection of these species, intestine becomes porous through the epithelial layer and ultimately become sieve-like. The muscularis mucosa were fully disrupted and damaged by the parasites like, Djombangia penetrans, Capingenoides batrachii, Pseudocaryophylaeus indicus, Procamallanus benglalensis and Spiracamallanus olsenia. All these species generally capable of local damage primarily by direct cellular destruction and hemorrhage.

Islam et al. (2015) worked on histopathological studies of early and late stages of Epizootic Ulcerative Syndrome infected fishes from three natural ponds at Demra, Dhaka. Five different types of fresh water wild fishes such as Anabas testudineus,

Channa punctatus, Colisa fasciatus, Mustus vittatus and Puntius ticto were collected. In this study, a prevalence of 64% (322/500) was recorded. Channa punctatus was found to be the most infected fish among the examined fishes. Petechia haemorrhages and moderate necrosis with melanomacrophages and multinucleated giant cells without fungal hyphae were pronounced in the early stages in the muscles. Moderate to severe necrosis friable tissues processing trailing fungal hyphae associated with fungal, protozoan and bacterial infection may have caused denuding or total erosion of the affected tissues. Extensive ulcers and high mortality were prominent in the late stages of infection. Cystic granulomas associated with multinucleated giant cells often engulfing fungal hyphae were the most characteristic features at the late stages in EUS affected fish. Other observations made were muscle degeneration, surrounding perforated muscle fibres and frequent degeneration of the blood vessel walls. However, the causative link between EUS and the observed histopathological features needs to be further elucidated.

Biochemical composition of (fresh) fish:

Johnstone (1918) analyzed the amount of fat in Halibut and the ranged from 0.5% - 9.6% where the protein content remained constant at close to 18%.

Stansby (1954) found the micronutrient content of the edible flesh of certain freshwater fishes and those were 76.8% moisture, 1.2% ash, 5% fat and 19% protein.

Jafri (1968a, 1968b and 1969) published a series of work on the seasonal changes in the biochemical compositions of common carp Cirrhina mrigala, catfish Mystus seenghala, freshwater murrel Ophiocepfalus punctatus and catfish Wallagonia attu. He indicated that the nutritive value of W. attu is higher than that of M. seenghala. He determined the changes in fat, moisture, protein and ash contents. The highest fat content in the muscle coincided with the period of peak ripeness. The protein cycle in various tissues showed a close relationship with maturation and spawning. Protein value in all the tissues was generally low during the winter.

Jafri (1969) worked on the seasonal changes in the biochemical composition of common carp and cat fish including W. attu. He indicated that the nutritive value of W. attu is higher than that of Mystus seenghala.

People of all ages from children over a year to older persons cen enjoy fish, because its protein is highly digestible (Nittleton, 1985). The protein from fish source would of utmost importance in supplying the nutritional need for the under nourished children as well as pregnant and lactating woman. Thus fish protein is the best animal protein and very much essential for human body development, but parasitic infestation interferes with the protein contents of fish body. Fish proteins comprise all the ten essential amino acids in desirable strength for human consumption. Aside from the main components such as moisture, protein, fat and ash, fish contains many other important micro nutrients (Calcium, phosphorus, iron, vitamins etc.). It is rich of essential dietary requirements constituted of protein (6-28%), moisture (28-90%), oil (0.2 – 64%), ash (0.4 – 1.5%), carbohydrate 0.6% (maximum), vitamins: A,B,C,D and E. Fishes are also good source of riboflavin, iron, calcium, phosphorus and magnesium (Banu et al. 1991).

Roopma (2013) reported to investigate the effect of frozen storage on the proximate, biochemical and microbial profile of the muscle of a silurid cat fish (Wallago attu). The fish muscle was subjected to the frozen storage for a period of one month and the analysis was carried out at an interval of 10 days. It was observed that proximate composition viz. protein, lipid, moisture and ash content decreased significantly (P<0.05) with increase in the duration of frozen period. The fresh (unfrozen) samples revealed the highest values for all i.e.15.45±0.2% for protein, 4.02±0.04% for lipid, 81.66±0.03 for moisture and 1.48±0.1% for ash while the least values were observed at the end of one month frozen storage period i.e.10.14±0.015%, 2.36±0.03%, 74±0.05% and1.33±0.02% for protein, lipid, moisture and ash respectively. Thus, considering the importance from consumer point of view, these studies reveal that a significant loss is observed in fish during frozen storage. However, it could be implied that fish could be kept under frozen conditions when preservation is of utmost importance, so as to retain its taste and nutrition.

Zaman and Khanum (2013) worked on proximate analysis of Mystus aor (Hamilton) and Mystus bleekeri (Day) in relation to parasitic infestation. A total 1011 Mystus aor and 1039 Mystus bleekeri were examined during January 2004 to December 2005. The results of the biochemical analysis revealed that protein and carbohydrate contents were found higher in M. bleekeri than in M. aor, while, lipid content was much higher in M. aor. In uninfected M. aor, the percentage of moisture and lipid (68.54 ± 1p.40 g/100g and 5.70 ± 0.45 g/100g) observed higher than uninfected M. bleekeri (67.11 ± 1.59 g/100g and 4.49 ± 0.33 g/100g) while, the values of protein and carbohydrate contents were higher in uninfected M. bleekeri than uninfected M. aor. In infected M. aor and M. bleekeri, the percentage of moisture (72.38 ± 1.5 g/100g and 72.85 ± 1.52 g/100g) found higher than uninfected one. The percentage of protein, lipids and carbohydrate were higher in uninfected fishes than in the infected fishes. Moisture content in both the catfishes found higher during hot and wet seasons and lower in dry season, while, the value of carbohydrate found higher in dry season and comparatively lower in hot and wet seasons.

Parasites infestation in relation to climatic factors (Temperature, Rainfall, Humidity):

The environmental factors including climate, season and rainfall play an important role in the development of helminth parasites. Rising concentrations of greenhouse gases in the atmosphere are causing global climate change. In the coming decades, global average temperatures will increase, rainfall patterns will change, extreme weather events will become more severe, sea levels will rise and numerous other environmental changes will occur (IPCC 2007). Agriculture will be affected, with impacts on food security. Fisheries and aquaculture will also feel the heat.

Climate change may directly affect fishery production along many pathways. Fish reproduction, growth and migration patterns are all affected by temperature, rainfall and hydrology (Ficke et al. 2007). Changes in these parameters will therefore shift patterns of species abundance and availability. Saltwater intrusion caused by rising sea levels may threaten freshwater fisheries while, at the same time, creating opportunities for catching and

41 cultivating high-value brackish or marine species (World Fish Center 2007). Changes in precipitation will affect seasonal flooding patterns that drive inland fish production. While greater wet season flooding may boost production in some inland fisheries, drier dry seasons may threaten stocks of both wild and cultured fish.

In the context of long-term and climate change scenarios, rising sea-level and water temperatures may have direct effects on the fish parasite composition within a respective habitat. Only very few freshwater habitats, however, are under pristine conditions, and anthropogenic species introduction connected to fisheries combined with regular migration events of neozoons alter the regular fish and parasite fauna. Most marine environments have suffered heavy fishing pressure over the last century. Anthropogenic changes have greatly altered the fish species composition, especially of large predators at high trophic levels (Hutchings and Baum 2005; Baum and Worm 2009). This has measurable effects even on life history traits, substantially changing age and size at maturation (Sharpe and Hendry 2009). Consequently, fish parasite numbers that are related to their changing host numbers may also change with a shift in environmental conditions. A conclusive description of the circumstances under which parasites can be used as indicators of environmental impact, however, still remains difficult (Vidal-Martı ´nez et. al. 2010).

The aquatic environment can be studied either directly by a regular monitoring of water quality parameters or indirectly by using bioindicators (Palm and R€uckert 2009), such as fish parasites (Galli et al. 2001). These organisms react on specific environmental conditions or change, leading to a wide range of applications (bioindication for water quality, MacKenzie et al. 1995; environmental stress, Landsberg et al. 1998; pollution, Khan and Thulin 1991; Yeomans et al. 1997). Vidal-Martı ´nez et al. (2010) generally distinguished between accumulation or effect bioindicators, where organisms efficiently take up substances in the former or are used to detect environmental impact in the latter. This is done while recording a definite change in their physiology, chemical composition, behaviour, or number. Also other parasite metrics such as diversity indices or species richness can be a source of information, demonstrating a possible effect of specific environmental conditions on the fish parasite community.

The presence of parasites within the environment often becomes evident after a massive infestation causing clinical signs or leading to mortality of the infected hosts. Such a situation can be combined with biotic or abiotic changes in the environment (M€oller, 1987), in the application of fish parasites as environmental indicators. Knowledge of the biology of the parasite and its host(s), the host– parasite relationship and the environment can help to detect environmental change.

(a)Temperature

The study from the University of Leicester revealed that global warming had the potential to change the balance between parasite and host -- with potentially serious implications for fish populations. The researchers from the University of Leicester's Department of Biology also observed behavioural change in infected fish -- suggesting parasites may manipulate host behaviour to make them seek out warmer temperatures. And they discovered that whilst parasites grew faster in higher temperatures, the host's growth rate slowed.

The scientists found that parasitic worms infecting stickleback fish grew four times faster in experimentally infected sticklebacks raised at 20°C than when raised at 15°C. In contrast, the fish grew more slowly at the higher temperature, suggesting that fish parasites cope with higher temperatures much better than the fish they infect. In a follow up study, the authors also showed that fish infected with the largest worms showed a preference for warmer water, suggesting that these parasites also manipulate the behaviour of host fish in ways that benefit the parasites and maximize their growth rates.The results provide some of the first evidence that increasing environmental temperatures can lead to a shift in the delicate balance that exists between co-evolved hosts and parasites, increasing the speed with which parasites complete their life cycles that could lead to an increase in the overall level of parasitism in natural animal populations (Macnab et al. 2011).

(b) Rainfall

Being one of the most vulnerable countries of climate change induced disasters; Bangladesh is facing some basic and major changes in its climatic behavior and weather pattern. Now a day, erratic rainfall becomes very common in Bangladesh. Climate change has induced erratic extreme rainfalls in many parts of the world. This rate is increasing abruptly. Long term unmitigated climate change will "likely" exceed the capacity of people and the natural world to adapt (IPCC, 2007).

Some authors conclude that a high abundance of parasites is maintained in tropical environments throughout the year (Coley and Aide, 1991; Martin et. al., 2004), while others suggest that these parasites could show major temporal shifts due to changes in rainfall (Steinauer and Font, 2003). Recent studies on fish infections caused by digenean parasites (Jiménez-García and Vidal-Martínez, 2005) indicate the importance of seasonality in infection parameters of parasites in tropical ecosystems, suggesting a link between seasonal factors such as rainfall or temperature, the presence of new host cohorts and maximum variability of the infection parameters.

Humidity is the amount of water vapor in the air. Water vapor is the gaseous state of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table or humidex (Wikipedia, the free encyclopedia).

There are three main measurements of humidity: absolute, relative and specific. Absolute humidity is the water content of air at a given temperature expressed in gram per cubic metre. Relative humidity, expressed as a percent, measures the current absolute humidity relative to

44 the maximum (highest point) for that temperature. Specific humidity is a ratio of the water vapor content of the mixture to the total air content on a mass basis.

Humidity is one of the fundamental abiotic factors that defines any habitat, and is a determinant of which animals and plants can thrive in a given environment. The human body dissipates heat through perspiration and its evaporation. Heat convection to the surrounding air, and thermal radiation are the primary modes of heat transport from the body. Under conditions of high humidity, the rate of evaporation of sweat from the skin decreases. Also, if the atmosphere is as warm as or warmer than the skin during times of high humidity, blood brought to the body surface cannot dissipate heat by conduction to the air, and a condition called hyperthermia results. With so much blood going to the external surface of the body, less goes to the active muscles, the brain, and other internal organs. Physical strength declines, and fatigue occurs sooner than it would otherwise. Alertness and mental capacity also may be affected, resulting in heat stroke or hyperthermia (Hogan, 2010).

Humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature. Therefore, when applying more pressure to a gas saturated with water, all components will initially decrease in volume approximately according to the ideal gas law. However, some of the water will condense until returning to almost the same humidity as before, giving the resulting total volume deviating from what the ideal gas law predicted. Conversely, decreasing temperature would also make some water condense, again making the final volume deviate from predicted by the ideal gas law. Therefore, gas volume may alternatively be expressed as the dry volume, excluding the humidity content. This fraction more accurately follows the ideal gas law. On the contrary the saturated volume is the volume a gas mixture would have if humidity was added to it until saturation (or 100% relative humidity).

CHAPTER – 3

MATERIALS AND METHODS

Wallago attu and Rita rita were autopsied for collection of helminths and other parasites, for taxonomic identification of the parasites, histopathological studies, biochemical analysis, food contents, monthly and seasonal infestation of parasites, their organal distribution etc.

Collection of the host fish species:

Sampling area and study period: A total of 250 Wallago attu and 350 Rita rita were autopsied and examined during January 2011 to December 2012, from Swarighat under Dhaka district of Bangladesh.

Sampling technique, measurement of length, sex differentiation: After collection, the fishes were kept in an ice box with ice and carried to the Parasitology laboratory, Department of Zoology under University of Dhaka for the present observation. In the laboratory they were examined within 2-3 hours. On the arrival at the laboratory, the fishes were given serial numbers and then the total length and weight were measured. The sexes of each fish were identified according to Haq (1977). The area of genital pore was observed to be quite helpful for identification of the sexes (Hossain and Islam, 1983).

Length groups:

To study the relationship between size of the host and infestation of parasite, the total length of fish was measured from tip of the snout to the end of the tail. The total length of the fish was measured by using centimeter scale. The total length of each of the host fish was divided into four length groups, such as-

Wallago attu: a) 35 – 42 cm. b) 43 – 50 cm. c) 51 – 58 cm. d) 59 – 66 cm.

Plate No. 1

Swarighat area

Fig. The location of monthly sample collecting area (shaded area)

Plate No. 2

Fig. Wallago attu

Fig. Rita rita

Rita rita:

a) 22 – 26 cm. b) 27 – 31 cm. c) 32 – 36 cm. d) 37 – 41 cm.

Identification of host fishes: Identification of Wallago attu ((Bloch and Schneider 1801) and Rita rita were done following Day (1878), Lagler (1956), Shafi and Quddus (1982) and Rahman (1989).

Examination and collection of parasites: The fishes were examined for external symptoms by a magnifying glass. Skin, fins, body surface, tail etc. were observed very finely to see the pathological condition such as ulcers, scars, cysts and injuries. Gills were scraped carefully and cleaned by forcep or needle to collect the gill parasites.

Isolation, fixation, staining and preservation of helminth parasites:

The helminth parasites were detected by both macro and microscopically into different groups: Trematoda, Cestoda, Nematoda and Acanthocephala. The parasites belonging to the major groups were separated and counted. In many cases some larval and juvenile stages were also observed.

Once the genus and species of each group were identified and familiarized, the parasites were easily separated and counted directly. For microscopic examination and identification, the helminthes were fixed and preserved in different suitable preservatives for each group and kept in separate vial. The trematodes and cestodes were fixed in acetic-formalin-alcohol (AFA), stained in borax-carmine or Semichon’s aceto-carmine; cleared in lactophenol and then mounted in Canada balsam. The nematodes and acanthocephalan were fixed in glycerin alcohol, stained in borax carmine, cleared in lactophenol followed by permanent mount on Canada balsam (Cable 1963).

Taxonomic identification of the parasites: For taxonomic classification of the helminth parasites, Yamaguti (1958, 1959 and 1961) and other relevant reference articles were consulted.

Collection of information about climatic factors (Temperature, Rainfall, Humidity): The information about climatic factors i. e. temperature, rainfall and humidity were collected from “Bangladesh Meteorological Department (BMD)”, Meteorological Complex, Agargaon, Dhaka – 1207.

Histopathological examination:

Tissue collection: The affected parts and organs of the fish, e.g. skin, liver, muscles, kidney, swim bladder and alimentary canal were separated and treated according to the methods instructed by Drury and Wallington (1967) for histological studies. After detection, the affected tissues were carefully fixed by a gradual addition of 10% Buffered neutral formalin solution.

Technique for histological study: The methods of Gray (1964) and Humason (1979) were followed for the preparation of the permanent histological slides. For preparation of histological slides, the tissue materials were kept in 10% Buffered neutral formalin solution for 24-48 hr for fixation, dehydrated in ascending grades of ethanol (50%, 70%, 90% and 100%), impregnated and embedded in paraffin and sectioned at 5µ. Sections were mounted on slides, deparafined by low grading and stained with haematoxylin and counter stained with eosin, dehydrated and finally mounted in Canada balsam.

Analysis of collected food items from the stomach of fish: To establish the food habits of W. attu and Rita rita, the stomach contents were analyzed by occurrence method (Hynes, 1950). Stomach contents were examined and the individual food items was stored out and identified with the aid of a dissecting microscope. The number of

50 stomachs in which each item occurred was recorded and expressed as a percentage of the total number of stomachs examined (Forbes, 1888). Stomachs with food were noted and the food items were grouped into 6 categories, as given below, according to the dominance of the particular group taken in by the fish as food item (Mellanby, 1963; Cannon,1973; Hyslop, 1980):

Category 1: small fishes, whole or remains of scales, bones, skin, flesh etc. Category 2: Crustaceans (Copepods, crayfishes, ostracod, crabs etc.) Category 3: Insects (eggs, wings, legs of arthropods, fleas, beetles, aquatic insects, pupae etc.) Category 4: Mollusca (Broken or empty shells, mantles of gastropods, pelecypods) Category 5: Plants and others (Vegetables materials, seeds, algae, organic matters, sand, mud, debris etc.)

Preparation of samples for the biochemical analysis:

The weighted samples of fishes were thoroughly washed with saline water (0.75%) and dried by soaking them with filter papers. The dried and cleaned fishes were treated separately as required by the specific methods of analysis for different nutrient content of Wallago attu and Rita rita. For the determination of each type of nutrient, every analysis was repeated 3-5 times and the mean value was recorded.

Proximate analysis of tissue sample:

The washed materials were soaked with blotting paper followed by filter paper at room temperature to remove the surface water. These were immediately kept in desiccators to avoid further evaporation of moisture from the materials. The samples become ready for the determination of their proximate composition such as the moisture content, protein, fat and carbohydrate. These determinations were made according to the method described by Gopalan (1971) and A.O.A.C. (1975).

Methods for analytical determination of nutrient contents:

1. Determination of moisture content: The fish sample (3-5 gm) was taken in a constant weight crucible. It was then dried at 100-105º C temperature in an oven for 4 hours and cooled in a desiccators and weight again. Healing, cooling and weighting were continued until a constant weight was obtained.

Calculation: Initial weight = Sample weight + crucible weight (Before heating)

Final weight = Sample weight + crucible weight (After heating)

Initial weight – Final weight Percentage of moisture = ------Sample weight

2. Determination of protein content:

Principle: The protein content of a foodstuff may be obtained by estimating the nitrogen content of the material and multiply the nitrogen value by 6.25. This was referred to as crude protein content, since the non-protein nitrogen (NPN) present in the material was taken into consideration in the present investigation.

The estimation of nitrogen was made by modified Kjeldahl method (Gopalan, 1971), which depends on the fact that organic nitrogen when digested with concentrated sulfuric acid in the presence of a catalyst was converted into ammonium sulphate. Ammonia liberated by making the solution alkaline, was distilled into a known volume of standard acid, which was then back titrated.

Reagent preparation:

1) Digestion mixture: Potassium sulphate and Copper sulphate in a ratio of 98 g: 2g, were powdered with, mortar pestle and mixed well. 2) Sulphuric acid solutions (0.1 N): Concentrated sulphuric acid (2.78 ml) was added in distilled water and the volume was made up to 1000 ml. The solution was standardized by standard sodium carbonate (0.1 N) solution. 3) Sodium hydroxide solution (0.1 N): Sodium hydroxide (4 gm) was dissolved in distilled water and the volume was made up to 1000 ml. It was standard by the standard sulphuric acid (0.1 N) solution. 4) Sodium carbonate solution (0.1 N): Anhydrous sodium carbonate (5.3 gm) was dissolved in distilled water and the volume was made upto 1000 ml. 5) Sodium hydroxide (40%): Sodium hydroxide (40%) was dissolved in distilled water and the volume was made up to 100 ml. 6) Methyl red indicator: Methyl red indicator (0.1 g) was dissolved in 60 ml alcohol and the volume was made up to 100 ml with distilled water.

Procedure: According to principle, Kjeldahl’s method consists of following steps: a) Digestion of sample b) Distillation c) Titration

a) Digestion: The sample was taken in weighting paper and measured accurately. This sample was poured in a 500 ml clean and oven dried Kjeldahl flask to which 5 gm of digestion mixture and 25 ml of pure concentrated sulphuric acid were added. To avoid frothing and bumping, a glass rod was placed inside the flask. A blank flask was carried with all reagents except sample material for the comparison. These flasks were then heated in a Kjeldahl digestion chamber initially at low temperature (10º C) until the mixture no longer froths and then temperature was increased to 60º C and heating was continued until the solution become colorless. At the end of digestion period the flasks were cooled and diluted with 100 ml distilled water. A small piece of litmus paper was placed in the solution and the reaction was found to be acidic.

b) Distillation:

The distilling set of Kjeldahl apparatus was thoroughly washed with distilled water before starting the distillation experiment. 25 ml of 0.1 N sulphuric acids was taken into the receiving 250 ml conical flask. In a measuring cylinder 75 ml of 40% Sodium hydroxide was taken and it was carefully poured down the side of the Kjeldahl flask. The litmus paper appeared blue indicated the solution became alkaline. The mouth of the flask was closed with a stopper containing connecting tube, which was ultimately connected to the ammonia receiving flask containing 0.1 N sulphuric acid. The mixture was boiled at such a rate that water and ammonia distilled over at a steady moderate rate. The heating was not too slow so that the sulphuric acid solution might be sucked into the Kjeldahl flask and not too fast so that the distilling ammonia did not escape the sulphuric acid without absorption.

c) Titration:

Ammonia absorbed in the receiving flask containing 0.1 N sulphuric acid was titrated with 0.1 N sodium hydroxide using 3 drops of methyl red as indicator. Similarly a reagent blank was distilled and titrated.

Calculation: The calculation of the protein content of the sample on the percentage basis was given by the following formula:

Percentage of protein = (c-b) × 14d × 6.25 × 100 a × 1000 Where,

a = Sample weight (g) b = Volume of sodium hydroxide required for the back titration and to neutralize 25 ml of

0.1 N H2SO4 (for sample) c = Volume of sodium hydroxide required for the back titration and to neutralize 25 ml of

0.1 N H2SO4 (for blank) d = Normality of sodium hydroxide used for titration, conversion factor of nitrogen to protein is 6.25, atomic weight of nitrogen is 14.

3. Determination of fat content:

Reagents of this determination are Chloroform : Methanol solution (Chloroform was mixed with Methanol in the ratio of 2:1) and Sodium chloride solution (0.58%) {sodium chloride (0.58g) was dissolved in distilled water and the final volume was made up to 100 ml }.

Reagent preparation:

1) Chloroform: Methanol solution- Methanol solution was mixed with Methanol in the ratio of 2:1. 2) Sodium chloride solution (0.58%) - Sodium chloride (0.58%) was dissolved in distilled water and the final volume was made up to 100 ml.

Procedure:

The moisture free sample (5g) was taken in a conical flask and to it 100 ml of Chloroform : Methanol solution (2:1) was added. The sample was allowed to stand for overnight and was filtered. The filtrate was taken in separating funnel and to it 0.58% Sodium chloride solution (20ml) was added. The separating funnel was vigorously shaked for proper mixing and allowed to stand for 4-6 hours. The lower phase was then collected and washed with Sodium chloride solution repeatedly till the lower phase was clear. Finally the lower phase was collected in a dry weighted conical flask. The fat was then estimated gravimetrically.

Calculation:

Percentage of fat = Weight of extract × 100 Sample weight

4. Determination of carbohydrate content: The content of available carbohydrate was calculated by difference i.e. by subtracting the sum of the value (per 100 gm) for moisture, ash, protein and fat from 100 gm.

5. Determination of calorie content: The calorie content of the fish flesh was calculated by multiplying by carbohydrate, protein and fat by 4,4 and 9 respectively.

Statistical techniques for analysis of data:

In the present study, some terms have been expressed as required concepts related to the number of the hosts in sample infected with a particular species of parasite groups and to the number of individuals of a particular species in each host in a sample (Margolis et al. 1982). Statistical calculation of data of the present observation was done on a personal computer. The SPSS program was utilized for statistical analyses which were obtained by the following formulas-

Prevalence == Percent of host infected

Number of host infected == ------× 100 Number of host examined

Intensity == Average number of parasites in each infected host

Total number of parasites == ------Number of host infected

Standard deviation== dispersion of probability about the highest point S = √ ∑ (x - x−) n where, S = Standard deviation x = the individual value x− = the arithmetic mean n = number of observation

The simple significance student “t-test”: It has been done for the comparison of the results and data of prevalence and intensity of the two species of fishes in two successive years (2011 and 2012).

Chi-square x² test: (O - E) ² x² = ∑ ------E Where, O = Observed number E = Expected number

Significant correlation: To find out the correlation (if any) of the prevalence and intensity of parasites with the size, season, sexes and food of the hosts. Correlation-coefficient tests were calculated by Linear regression and Multiple regression methods.

Microphotograph: The photomicrograph of the parasites and the histological sections were taken by a fitted camera (Olympus Microscope Adapter) with compound microscope (Olympus Model) in the Parasitology Laboratory, Dept. of Zoology, University of Dhaka.

Seasons: Rainy = July to October Winter = November to February Summer = March to June

CHAPTER – 4

OBSERVATION AND RESULTS

4.1- The communities of parasites

Community of ecto-parasites

Arthropoda

Argulus foliaceus (Linnaeus, 1758)

Lernaea cyprinacea (Linnaeus, 1758)

Community of endo-parasites

Trematoda

Isoparorchis hypselobagri (Billet, 1898)

Macrolecithus gotoi (Hasegawa et Ozaki, 1926)

Magnacetabulum trachuri (Yamaguti, 1934)

Notoporus leiognathi (Yamaguti, 1938)

Saccacoelium obesum (Looss, 1902)

Sterrhurus musculus (Looss, 1907)

Clinostomum piscidium (Southwell et Prashad, 1918)

Cestoda

Polyoncobothrium polypteri (Leydig, 1853)

Nematoda

Cosmoxynemoids aguirrei (Travassos, 1949)

Contracaecum L3 larva (Railliet et Henry, 1912)

Ascaroid larva (Railliet et Henry, 1915)

Acanthocephala

Echinorhynchus kushiroense (Fujita, 1921)

Pallisentis ophiocephali (Thapar, 1930)

Acanthocephalus aculeatus (Van Cleave, 1931)

Pallisentis umbellatus (Van Cleave, 1928)

Cavisoma magnum (Southwell, 1927)

Corynosoma alaskense (Golvan, 1959)

Corynosoma strumosum (Rud, 1802)

The communities of parasites in Wallago attu and Rita rita

The present investigation was done on two species of fish, Wallago attu and Rita rita. Out of 250 W. attu, 59 were infected (prevalence – 23.6%) and out of 350 R. rita, 87 were infected (prevalence – 24.8%) with different ecto-parasites (Fig-1). In the present study, one species of ecto-parasite (Argulus foliaceus) was collected and identified from W. attu, while, another species of ecto-parasite (Lernaea cyprinacea) found in R. rita. The intensity of ecto-parasite at per infected W. attu was 3.11 ± 1.47 and in R. rita was 3.34 ± 1.62 [Fig -2, Table – 1].

Table 1. Diversity of ecto-parasites in Wallago attu and Rita rita

Name Parasite No. of host No. of Prevalence No. worm Intensity of the species examined host (%) collected fish host infected

Wallago Argulus 250 59 23.6 184 3.11 ± 1.47 attu foliaceus

Rita Lernaea 350 87 24.8 291 3.34 ± 1.62 rita cyprinacea

25 24.8

24.5 23.6 24

23.5 Prevalence (%) Prevalence 23

Argulus foliaceus (W. Attu) Lernaea cyprinacea ( R. Rita) Ecto-parasites

Fig 1. Prevalence of ecto- parasites in W. attu and R. rita

Out of 250 W. attu, 86 were infected (prevalence – 34.4%) and out of 350 R. rita, 226 were infected (prevalence – 64.57%) with different helminth parasites. In the present study, ten species of parasites from different helminth groups were collected and identified from W. attu, while, eight species of parasites found in R. rita. The intensity of parasites at per infected W. attu was 1.67± 0.93 and in R. rita was 2.64± 1.91 [Table – 2].

3.35 3.34 3.3

3.25 3.2 3.15 3.11

3.1 Intensity 3.05 3 2.95

Argulus foliaceus (W. Attu) Lernaea cyprinacea ( R. Rita) Ecto-parasites

Fig 2. Intensity of ecto- parasites in W. attu and R. rita

Prevalence of infestation in male W. attu and R. rita were 35.8% and 70% while, in female W. attu and R. rita were 33.5% and 56.4% respectively. Intensity of parasites in male W. attu and R. rita were 1.21 ± 0.41 and 1.52 ± 0.78. On the other hand, intensity of parasites in female W. attu and R. rita were 1.98 ± 1.04 and 4.73 ± 1.59 [Table – 2].

During Jan’11 - Dec’11, a total of 124 W. attu were examined and among them 51 were infected, the prevalence of infestation was 41.13% and the intensity of the parasites were 1.84 ± 0.46. In the next year (Jan’12-Dec’12), 126 numbers of host fishes were examined and 35 hosts were infected, the prevalence and the intensity of parasite was 27.77% and 1.4 ± 0.35 [Fig – 3].

In case of R. rita, (Jan’11-Dec’11) a total no. of 201 fishes were examined and among them 173 were infected, the prevalence of infestation was 86.06% and the intensity of the parasites were 2.32 ± 0.58. In the next year (Jan’12-Dec’12), 149 numbers of host fishes were examined and 53 hosts were infected, the prevalence and the intensity of parasites were observed 35.57% and 3.68 ± 0.92 [Fig – 3].

Table 2. Diversity of endo-parasites in Wallago attu and Rita rita

Factors Wallago attu Rita rita

Number of fish examined 250 350

Number of fish infected 86 226

Prevalence of infestation 34.4% 64.57%

Total number of parasites 144 597 collected from host fishes

Total number of parasite 10 8 species collected from host fishes

Mean intensity per infected fishes ± 1.67± 0.93 2.64± 1.91 standard deviation

Prevalence of infestation in Male 35.8% 70%

Prevalence of infestation in 33.5% 56.4% Female

Intensity of parasites in Male 1.21 ± 0.41 1.52 ± 0.78

Intensity of parasites in Female 1.98 ± 1.04 4.73 ± 1.59

In W. attu, among the ten endo-parasite species, three were belong to Trematoda (Isoparorchis hypselobagri, Macrolecithus gotoi, Magnacetabulum trachuri); two belong to Nematoda (Contracaecum L3 larva, Cosmoxynemoids aguirrei); one belong to Cestoda (Polyoncobothrium polypteri); four belong to Acanthocephala (Echinorhynchus kushiroense, Pallisentis ophiocephali, Acanthocephalus aculeatus, Pallisentis umbellatus).

In R. rita, eight species of endo-parasites were collected; among them four were from Trematoda (Notoporus leiognathi, Saccacoelium obesum, Sterrhurus musculus, Clinostomum piscidium); one from Nematoda (Ascaroid larva) and three from Acanthocephala (Cavisoma magnum, Corynosoma alaskense, Corynosoma strumosum) [table – 4].

4 3.68 3.5 3 2.32 2.5 1.84 2 Prevalence 1.4 1.5 Intensity 86.06% 1 41.13% 35.57% 0.5 27.77% 0 W. attu W. attu R. rita R. rita Jan'11- Jan'12- Jan'11- Jan'12- Dec'11 Dec'12 Dec'11 Dec'12

Fig 3. Comparison of prevalence and intensity of endo- parasites between W. attu and R. rita in 2011 and 2012

Table 3. Analysis of endo-parasites in Wallago attu and Rita rita

Host fish 2011 2012 P-value Wallago attu Prevalence (%) 41.1 27.8 0.027* Intensity of 1.84 1.40 0.000** parasites Rita rita Prevalence (%) 86.1 35.5 0.000* Intensity of 2.23 3.68 0.000** parasites *p-value is found using proportion test; ** p-value is found using independent two sample t- test

Table -3 shows the result of “proportion test” and “t-test”. In case of “proportion test”, the overall proportion of infected W. attu differs significantly at 5% level of significance between two periods 2011 and 2012. It reveals that the prevalence

of infected fish during 2012 (27.8%) was significantly lower than that of 2011 (41.1%) with P < 0.05. Similar trend was shown in case of R. rita. The prevalence differs with strong significant (P < 0.05) even at 1% level of significance.

In case of “t-test”, the mean intensity of W. attu differs significantly between 2011 and 2012 and the intensity of infected fish in 2011 (1.84 ± 0.46) was significantly higher than 2012 (1.40 ± 0.3) with P < 0.05. Similarly, in case of R. rita, the intensity was found to be strongly significantly associated (P < 0.05) in both the years.

Table 4. List of the parasites collected from W. attu and Rita rita during the study period (Jan’ 11 – Dec’ 12)

Group W. attu R. rita

Isoparorchis hypselobagri Notoporus leiognathi

Macrolecithus gotoi Saccacoelium obesum

Magnacetabulum trachuri Sterrhurus musculus Trematoda Clinostomum piscidium

Cosmoxynemoids aguirrei

Nematoda Contracaecum L3 larva Ascaroid larva

Cestoda Polyoncobothrium polypteri -

Acanthocephala Echinorhynchus kushiroense Cavisoma magnum

Pallisentis ophiocephali Corynosoma alaskense

Acanthocephalus aculeatus Corynosoma strumosum

Pallisentis umbellatus

Arthropoda Argulus foliaceus Lernaea cyprinacea

Table 5. Prevalence and intensity of parasites in W. attu and R. rita

Wallago attu Rita rita Parasite Parasite species No. of Prevalence of No. of Prevalence of groups hosts infestation hosts infestation infected (%)& infected (%) & Intensity Intensity Isoparorchis hypselobagri 13 5.2%, - - 1.54± 0.39 Macrolecithus gotoi 08 3.2%, - - Trematoda 1.87± 0.47 Magnacetabulum trachuri 11 4.4%, - - 1.18± 0.29 Notoporus leiognathi - - 45 12.8%, 2.42±0.61 Saccacoelium obesum - - 43 12.3%, 2.42±0.61 Sterrhurus musculus - - 39 11.1%, 1.82±0.46 Clinostomum piscidium - - 34 9.7%, 2.03±0.51 Cestoda Polyoncobothrium polypteri 05 2%, 1 ± 0 - - Cosmoxynemoids aguirrei 03 1.2%, 3± 0.75 - - Nematoda Contracaecum L3 larva 10 4%, 1.3± 0.33 - - Ascaroid larva - - 16 4.6%, 3.31±0.83 Echinorhynchus kushiroense 06 2.4%, - - 2.16± 0.54 Pallisentis ophiocephali 15 6%, 1.4± 0.35 - -

Acanthocephalus aculeatus 10 4%, 1.8± 0.45 - -

Acanthocephala Pallisentis umbellatus 05 2%, 3.4± 0.85 - -

Cavisoma magnum - - 18 5.1%, 2.72± 0.68 Corynosoma alaskense - - 19 5.4%, 4.63± 1.16 Corynosoma strumosum - - 12 3.4%, 4.5± 1.12 Arthropoda Argulus foliaceus 59 23.6%, - - 3.11 ± 0.77 Lernaea cyprinacea - - 87 24.8%, 3.34 ± 0.83

Table 6. Percentage of helminth parasites in W. attu and R. rita Wallago attu Rita rita Parasites No. of Occurrence % in No. of Occurrence % in parasites in total parasites in total collected group(%) collected group(%)

Isoparorchis hypselobagri 20 42 13.88 - - -

Macrolecithus gotoi 15 31 10.41 - - -

Magnacetabulum trachuri 13 27 9.02 - - -

Notoporus leiognathi - - - 109 31 18.26

Saccacoelium obesum - - - 104 29 17.42

Sterrhurus musculus - - - 71 20 11.89

Clinostomum piscidium - - - 69 20 11.55

Total 48 100 33.31 353 100 59.12

Polyoncobothrium polypteri 05 100 3.47 - - -

Cosmoxynemoids aguirrei 09 41 6.25 - - -

Contracaecum L3 larva 13 59 9.02 - - -

Ascaroid larva - - - 53 100 8.87

Total 22 100 15.27 53 100 8.87

Echinorhynchus kushiroense 13 19 9.02 - - -

Pallisentis ophiocephali 21 30 14.58 - - -

Acanthocephalus aculeatus 18 26 12.5 - - -

Pallisentis umbellatus 17 25 11.8 - - -

Cavisoma magnum - - - 49 26 8.21

Corynosoma alaskense - - - 88 46 14.74

Corynosoma strumosum - - - 54 28 9.04

Total 69 100 47.9 191 100 31.99

Percentage of helminth parasites in W. attu and R. rita

In the present investigation, trematodes and acanthocephalans were found most dominant among the parasites (3 trematodes and 4 acanthocephalas in W. attu and 4 trematodes and 3 acanthocephalas in R. rita) in both the hosts (Table 5). The trematodes were 33.31% and acanthocephala were 47.9% of the total number of parasites recovered from W. attu. On the other hand, the trematodes were 59.12% and acanthocephalans were 31.99% of the total number of parasites recovered from R. rita (Table-6).

Macrolecithus gotoi was recovered only from W. attu and the prevalence was 3.2% with 1.87 ± 0.46 as mean intensity (Table- 5). The occurrence of the trematode was recorded 10.41% of the total number of parasites collected and 31% of the trematode fauna observed (Table- 6).

Isoparorchis hypselobagri was the most numerically dominant species in W. attu. The prevalence and mean intensity of this parasite were 5.2% and 1.54 ± 0.38 (Table-5). The occurrence of I. hypselobagri accounting for 13.88% of the total parasites and 42% of the trematode group in W. attu (Table- 6).

The another trematode Magnacetabulum trachuri in W. attu showed prevalence 4.4% and mean intensity 1.18 (Table- 5). This parasite composed 9.02% of the total parasite and 27% of the total number of trematodes (Table- 6).

The four trematodes found in R. rita are N. leiognathi, S. obesum, S. musculus and C. piscidium showed the prevalence 12.8%, 12.3%, 11.1% and 9.7% respectively and mean intensity 2.42 ± 0.61, 2.42 ± 0.61, 1.82 ± 0.46 and 2.03± 0.51 respectively (Table-5). They were comprised 18.26%, 17.42%, 11.89% and 11.55% respectively of the total parasites (Table- 6) and 31%, 29%, 20% and 20% observed respectively of the trematode group.

In W. attu, a total of four species of acanthocephalan were observed such as E. kushiroense, P. ophiocephali, A. aculeatus and P. umbellatus. They showed the prevalence were 2.4%, 6%, 4% and 2% respectively and mean intensity 2.16± 0.54 ,

1.4±0.35, 1.8± 0.45 and 3.4± 0.85 respectively (Table-5). They comprised 9.02%, 14.58%, 12.5% and 11.8% of the total parasites and 19%, 30%, 26% and 25% of the acanthocephalan group observed (Table-6).

On the other hand, a total of three species of acanthocephala were collected from R. rita. They were Cavisoma magnum, Corynosoma alaskense and Corynosoma strumosum with prevalence 5.1%, 5.4% and 3.4% and mean intensity 2.72±0.68, 4.63± 1.16 and 4.5±1.13. These parasites composed 8.21%, 14.74% and 9.04% of the total parasites while, 26%, 46% and 28% of the total number of acanthocephalan fauna were observed (Table – 5,6).

Among the nematode, the L3 larva of Contracaecum was found to be the most numerically dominant and also dominated the nematode fauna observed in the present study. It was found only in W. attu. The prevalence and mean intensity were found 4% and 1.3 ± 0.33. This parasite comprised 9.02% of the total parasite collected and 59% of the nematode obtained from W. attu ( Table – 5,6).

P. polypteri 6% I. hypselobagri Contracaecum L3 15% larva 12%

C. aguirrei M. gotoi 3% 9%

P. umbellatus 6%

M. trachuri A. aculeatus 13% 12%

E. kushiroense 7% P. ophiocephali 17%

Fig 4. Prevalence of helminth parasites in W. attu

In W. attu, the other nematode were Cosmoxynemoids aguirrei, showed 1.2% prevalence and 3± 0.75 as mean intensity (Table -5), this parasite accounting for 6.25% of the total parasites recovered from W. attu (Table – 6).

Ascaroid larva was the only nematode found in R. rita, with 4.6% prevalence and 3.31± 0.83 as mean intensity was moderately abundant comprising 8.87% of the total parasites (Table – 5,6).

The cestode Polyoncobothrium polypteri was only found in W. attu which was 3.47% of the total parasites (Table -5). The prevalence was recorded 2% with 1 ± 0 as mean intensity (Table - 5).

Ascaroid larva C. strumosum 7% N. leiognathi 5% 20% C. alaskense 9%

C. magnum 8%

S. obesum 19%

C. piscidium 15%

S. musculus 17%

Fig 5. Prevalence of helminth parasites in R. rita

Table 7. Infestation by helminth parasites of W. attu and R. rita P-value Host fish 2011 2012 Hypothesis (using proportion test) Proportion of H0: There is W.attu infected fish 41.13 27.77 no difference 0.026* (%) between the Number of 124 126 prevalence of fish examined infestation Proportion of during 2011 R.rita infected fish 87.50 35.33 and 2012 0.000** (%) Number of 201 149 fish examined * Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 7 shows the two sample binomial proportion test result. The overall proportion of infected W. attu differs significantly at 5% level of significance between two periods 2011 and 2012. It reveals that the prevalence of infected fish during 2012 (27.77%) was significantly lower than that of 2011 (41.13%) with P < 0.05. Similar tendency was shown in case of R. rita. The prevalence differs with strongly significant (P < 0.05) even at 1% level of significance.

Organal distribution of different parasites in W. attu and R. rita

In W. attu and R. rita, the parasite fauna was observed to occupy the stomach, anterior and posterior intestine, body cavity, swim bladder and the larval forms was found to be attached to the anterior intestine, liver and fat bodies. It was noted that a particular parasite was found to infect one or more organ in both host fishes (Table -8).

In W. attu, Magnacetabulum trachuri and Cosmoxynemoids aguirrei were found to be located in stomach, anterior and posterior intestine. Macrolecithus gotoi, Echinorhynchus kushiroense, Pallisentis ophiocephali, Acanthocephalus aculeatus, Pallisentis umbellatus were collected from anterior and posterior intestine.

Table 8. Organal distribution of helminth parasites in W. attu and R. rita

Host Name of the parasites Stomach Anterior Posterior Body Swim Total intestine intestine cavity bladder

Isoparorchis hypselobagri 0 0 0 0 20 20

Macrolecithus gotoi 0 05 10 0 0 15

Magnacetabulum trachuri 01 05 04 03 0 13

Echinorhynchus kushiroense 0 08 05 0 0 13

Pallisentis ophiocephali 0 14 07 0 0 21

Wallago Acanthocephalus aculeatus 0 07 11 0 0 18 attu Pallisentis umbellatus 0 11 06 0 0 17

Cosmoxynemoids aguirrei 02 02 04 01 0 09

Contracaecum L3 larva 0 0 0 13 0 13

Polyoncobothrium polypteri 02 03 0 0 0 05

Total 05 55 47 17 20 144

Notoporus leiognathi 21 66 18 04 0 109

Saccacoelium obesum 18 39 47 0 0 104

Sterrhurus musculus 51 15 05 0 0 71

Clinostomum piscidium 0 10 02 57 0 69

Rita rita Cavisoma magnum 18 31 0 0 0 49

Corynosoma alaskense 0 63 25 0 0 88

Corynosoma strumosum 0 43 11 0 0 54

Ascaroid larva 0 49 03 01 0 53

Total 108 316 111 62 0 597

Among the trematode, in W. attu, Isoparorchis hypselobagri was only found in swim bladder. The only cestode parasite, Polyoncobothrium polypteri in W. attu was collected from stomach and anterior intestine. The Contracaecum L3 larva was collected from body cavity.

In R. rita, Notoporus leiognathi, Saccacoelium obesum and Sterrhurus musculus were found in stomach, anterior and posterior intestine. Clinostomum piscidium and the Ascaroid larva were collected from anterior and posterior intestine and body cavity. Corynosoma alaskense and Corynosoma strumosum were found in anterior and posterior intestine.

Percentage of helminth parasites found in the various organs of W. attu and R. rita

In W. attu, the percentage of parasites present in different organs was: stomach – 3.5%, anterior intestine – 37.76%, posterior intestine – 32.9%, body cavity – 11.88% and swim bladder – 13.98% (Fig -6 a).

40% 37.76% 35% 32.90%

30% 25% 20%

15% Percentage 10% 11.88% 13.98% 3.50% 5% 0% Stomach An. Post. Intestine Body cavity Intestine Swim bladder Name of the organs

Fig 6 (a). Percentage of total helminth parasites found in various organs of W. attu

60% 52.93%

50% 40% 30% 18.09% 20% 18.60% Percentage 10% 10.38% 0% Stomach An. Intestine Post. Intestine Body cavity

Name of the organs

Fig 6 (b). Percentage of total helminth parasites found in various organs of R. rita

48.23% 50% 45% 40% 33.55% 35% 30% 25% 20% 15.38%

% of infection of % 15% 10% 2.79% 5% 0% Trematoda Acanthocephala Nematoda Cestoda

Parasite groups

Fig 7. Percentage of infestation of different helminth parasite groups in W. attu

In R. rita, the percentage of parasites present in different organs in: stomach – 18.09%, anterior intestine – 52.93%, posterior intestine – 18.6% and body cavity – 10.38% (Fig. 6 b).

Interpretation: In the present investigation, a comparative and detailed analysis of prevalence and intensity of helminth parasites, their organal distribution in W. attu and R. rita have been discussed. I. hypselobagri was the largest and most striking freshwater fish trematode recorded. A particular parasite was found to infect one or more organ in both host fishes (Table – 5-8).

Percentage of different parasite groups in W. attu and R. rita

The Acanthocephala showed the highest infestation 48.23%. The trematode parasites were 33.55%, nematodes 15.38% and the lowest infestation 2.79% observed by cestode in W. attu (Fig-7).

Among the different classes, the rate of infestation of trematodes in R. rita was 59.12%. The second highest infestation rate was 31.99% for acanthocephala and then the last group nematodes were 8.87% (Fig - 8).

59.12% 60%

50%

40% 31.99%

30%

20% % % infectionof 8.87% 10%

0% Trematoda Acanthocephala Nematoda

Parasite groupss

Fig 8. Percentage of infestation of different helminth parasite groups in R. rita.

Table 9. Comparative analysis for intensity of parasites during 2011 and 2012 (using Independent two sample “t test”) Host fish 2011 estimates 2012 estimates P-value Intensity of 1.84 1.4 parasites W. attu Number of 124 126 0.000** fish examined SD ± 0.46 ± 0.35 Intensity of 2.33 4.08 R. rita parasites Number of 201 149 0.000** fish examined SD ± 0.58 ± 1.02

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table - 9 shows two sample independent “t –test” for intensity of the parasites between 2011 and 2012. The mean difference of the intensity of parasites for W. attu between two years 2011 and 2012 was strongly statistically significant (P < 0.05). In case of R. rita, the intensity of parasites differs between these two periods was strongly significant (P < 0.05) at 5% level of significance.

CHAPTER – 4.2

Infestation of parasites in different months and seasons

Infestation of ecto-parasites in Wallago attu and Rita rita in relation to different months and seasons

In the present investigation, the prevalence and intensity of ecto-parasites (Argulus foliaceus in W. attu and Lernaea cyprinacea in R. rita) have been described according to different months and seasons. The overall recorded infestation of parasites species in both the host fishes were statistically analyzed to determine the seasonal variation during January 2011 to December 2012.

Regarding the yearly incidence, in W. attu, the prevalence of Argulus foliaceus was 16.9% in 2011 and 30.2% in 2012 (Table- 12). In R. rita, the prevalence of Lernaea cyprinacea was comparatively higher (32.9%) in 2012 than in 2011 (17.9%) [Table- 13].

Table 10. Infestation of W. attu and R. rita by Argulus foliaceus and Lernaea cyprinacea

Host fish Prevalence (%) Prevalence (%) P-value in 2011 in 2012 (using proportion test) W. attu 16.9 30.2 0.014** R. rita 17.9 32.9 0.001**

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 10 shows the result of “proportion test” between the prevalence of 2011 and 2012. The overall proportion of infected W. attu (by ectoparasite) differs significantly at 5% level of significance between two periods 2011 and 2012. It reveals that the prevalence of infected fish during 2012 (30.2%) was significantly higher than that of 2011 (16.9%) with P < 0.05. Similar tendency was shown in case of R. rita. The prevalence differs with strong significant (P < 0.05) at 1% level of significance.

In W. attu, ( Jan’11 – Dec’11), the prevalence of Argulus foliaceus was highest (40%) in November’11 (winter) and the highest intensity of parasites (5± 0) was observed in July’11 (rainy). The lowest prevalence (9.09%) was found in the month of Jan’11 (winter) and June’11 (summer) (Fig -9). The lowest intensity of infestation (2.5± 1.3) was observed in the month of Nov’11 (winter) (Fig -10).

In W. attu, the highest prevalence (45.45%) was found in January’12 (winter) and highest intensity (6.0± 0.0) of parasites found in December’12 (winter). The intensity of parasites found lowest (2.0± 1.0) in Feb’12 (winter) and Oct’12 (rainy) and the lowest prevalence (9.09%) observed in September’12 (rainy) (Table -12).

In R. rita, during Jan’11 – Dec’11, the maximum prevalence (31.2%) and intensity (5.5± 0.7) of Lernaea cyprinacea was observed in the month of Dec’11 and Nov’11 (winter). The lowest prevalence (11.7%) of infestation was in April’11 (summer) and Nov’11 (winter) (Fig – 11) and lowest intensity (3 ± 0) found in Feb’11 (winter).

Table 11. Infestation of W. attu and R. rita by ecto-parasites

P-value Host fish 2011 2012 (using “t” test) W. attu Mean 3.29 3.03 0.144 SD ± 1.06 ± 1.67 R. rita Mean 4.17 2.76 0.000** SD ± 1.30 ± 1.58 * Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 11 is shown two sample independent “t –test” for intensity of the parasites between 2011 and 2012. The mean difference of the intensity of parasites for R. rita between two years 2011 and 2012 was strongly and statistically significant (P <0.05). But in case of W. attu , the intensity of parasites differs between these two periods was not significantly associated (P > 0.05) with the infection of ecto- parasites.

Table 12. Monthly prevalence and intensity of Argulus foliaceus in W. attu (Jan’11– Dec’12)

Month No. of fish No. of fish Prevalence No. of Intensity of examined infected of infestation worms parasites (%) collected January 11 01 9.09 03 - February 10 00 00 00 - March 11 02 18.18 07 3.5± 0.7 April 10 01 10 04 - May 10 01 10 04 - June 11 01 9.09 03 - July 10 02 20 10 5± 0 August 10 02 20 06 3± 0 September 11 04 36.36 11 2.8± 1 October 09 00 00 00 - November 10 04 40 10 2.5± 1.3 December 11 03 27.27 11 3.7± 1.2 January 11 05 45.45 12 2.4± 1.1 February 9 03 33.33 06 2.0± 1.0 March 10 04 40 12 3.0± 2.2 April 11 04 36.36 13 3.3± 1.7 May 10 02 20 05 2.5± 0.7 June 11 04 36.36 12 3± 1.8 July 10 04 40 12 3± 1.8 August 10 04 40 13 3.3± 1.7 September 11 01 9.09 03 - October 10 03 30 06 2.0± 0.0 November 11 02 18.18 09 4.5± 3.5 December 12 02 16.66 12 6.0± 0.0

Prevalence (%) Prevalence 15

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 9. Monthly prevalence of Argulus foliaceus in W. attu (Jan’11– Dec’12)

3 Intensity

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 10. Monthly intensity of Argulus foliaceus in W. attu (Jan’11– Dec’12)

Table 13. Monthly prevalence and intensity of Lernaea cyprinacea in R. rita (Jan’11 – Dec’12)

Month No. of fish No. of fish Prevalence No. of Intensity of examined infected of infestation worms parasites (%) collected January 19 05 26.3 22 4.4± 0.9 February 17 03 17.6 09 3± 0 March 18 03 16.6 11 3.7± 0.6 April 17 02 11.7 10 5± 0 May 15 03 20 15 5± 1.7 June 17 03 17.6 16 5.3± 2.1 July 16 02 12.5 07 3.5± 0.7 August 16 03 18.7 12 4± 1 September 17 03 17.6 14 4.7± 1.5 October 16 02 12.5 07 3.5± 0.7 November 17 02 11.7 11 5.5± 0.7 December 16 05 31.2 16 3.2± 1.5 January 12 04 33.3 13 3.3± 2.1 February 14 06 42.8 18 3± 0.9 March 11 03 27.2 11 3.7± 2.3 April 11 05 45.4 20 4± 2.2 May 12 03 25 12 4± 0 June 11 04 36.3 09 2.3± 1.9 July 14 04 28.5 05 1.3± 0.5 August 13 03 23.1 03 1± 0 September 14 05 35.7 05 1± 0 October 13 03 23.1 12 4± 0 November 12 04 33.3 15 3.8± 1 December 12 07 58.3 18 2.6± 0.5

30 Prevalence Prevalence (%) 20

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 11. Monthly prevalence of Lernaea cyprinacea in R. rita (Jan’11 – Dec’12)

3 Intensity 2

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 12. Monthly intensity of Lernaea cyprinacea in R. rita (Jan’11 – Dec’12)

In 2012, the highest prevalence (58.3%) and intensity (4 ± 0) of infestation was found in Dec’12 (winter), April’12 and May’12 (summer). The lowest prevalence (23.1%) found in Aug’12 and Oct’12 (rainy) (Table – 13) and lowest intensity (1 ± 0) of parasites was observed in Aug’12 and Sep’12 (rainy) (Fig -12).

Infestation of endo-parasites in Wallago attu and Rita rita in relation to different months and seasons

In the present investigation, the prevalence and intensity of parasites have been described according to different months and seasons. The overall recorded infestation of parasites species in both the host fishes were statistically analyzed to determine the seasonal variation during January 2011 to December 2012.

Regarding the yearly incidence, in W. attu, the prevalence was 41.13% in 2011 and 27.77% in 2012 (Table-14,15). In R. rita, the prevalence was comparatively higher (86.32%) in 2011 than in 2012 (35.33%) (Table-16, 17).

In W. attu, (in Jan’11 – Dec’11), the prevalence of infestation was highest (72.72%) in December’11 and the highest intensity of parasites (2.33±0.58) was observed in February’11. The lowest prevalence (30%) was found in the month of February’11, May’11 and August’11. The lowest intensity of infestation (1.33± 0.33) was observed in the month of August’11 and October’11.

In 2012, the highest prevalence (44.44%) was found in February’12 and highest intensity (2.50± 0.63) of parasites found in November’12. The intensity of parasite found lowest (0.66± 0.16) in March’12 and lowest prevalence (18.18%) observed in September’12 and November’12 (Table-14, 15).

In R. rita, during Jan’11 – Dec’11, the maximum prevalence (100%) and intensity (2.75± 0.68) of infestation were observed in the month of July’11 and May’11. The lowest prevalence (73.68%) of infestation was in January’11 and intensity (2.12 ± 0.53) found in September’11.

Table 14. Monthly prevalence and intensity of helminths in W. attu (Jan’11– Dec’11)

Month No. of fish No. of fish Prevalence No. of Intensity of examined infected of infestation worms parasites (%) collected January 11 4 36.36 9 2.25±0.56 February 10 3 30 7 2.33±0.58 March 11 5 45.45 10 2.00±0.50 April 10 4 40 6 1.50±0.37 May 10 3 30 5 1.66±0.42 June 11 4 36.36 9 2.25±0.56 July 10 6 60 11 1.83±0.46 August 10 3 30 4 1.33±0.33 September 11 4 36.36 6 1.50±0.38 October 09 3 33.33 4 1.33±0.33 November 10 4 40 8 2.00±0.50 December 11 8 72.72 15 1.87±0.48 Overall 124 51 41.13 94 1.84±0.46

Table 15. Monthly prevalence and intensity of helminthes in W. attu (Jan’12 – Dec’12)

Month No. of fish No. of fish Prevalence No. of worms Intensity of examined infected of infestation collected parasites (%) January 11 3 27.27 5 1.66±0.42 February 9 4 44.44 6 1.50±0.37 March 10 3 30 3 1.00±0.25 April 11 4 36.36 4 1.00±0.25 May 10 2 20 3 1.50±0.37 June 11 3 27.27 5 1.66±0.42 July 10 2 20 4 2.00±0.50 August 10 3 30 4 1.33±0.33 September 11 2 18.18 3 1.50±0.37 October 10 3 30 4 1.33±0.33 November 11 2 18.18 5 2.50±0.63 December 12 4 33.33 4 1.00±0.25 Overall 126 35 27.77 50 1.4±0.35 Total 250 86 144 Jan’11-Dec’12 Mean 34.45 1.62 Jan’11-Dec’12

Table 16. Monthly prevalence and intensity of helminths in R. rita (Jan’11 – Dec’ 11)

Month No. of fish No. of fish Prevalence No. of Intensity of examined infected of infestation worms parasites (%) collected January 19 14 73.68 34 2.42±0.61 February 17 15 88.23 34 2.26±0.56 March 18 14 77.77 36 2.57±0.64 April 17 14 82.35 34 2.42±0.61 May 15 12 80.00 33 2.75±0.68 June 17 14 82.35 32 2.28±0.57 July 16 16 100.00 36 2.25±0.56 August 16 15 93.75 35 2.33±0.58 September 17 16 94.12 34 2.12±0.53 October 16 15 93.75 32 2.13±0.53 November 17 14 82.35 31 2.21±0.55 December 16 14 87.50 31 2.21±0.55 Overall 201 173 86.32 402 2.33±0.58

Table 17. Monthly prevalence and intensity of helminths in R. rita (Jan’12 – Dec’ 12)

Month No. of fish No. of fish Prevalence No. of worms Intensity of examined infected of infestation collected parasites (%) January 12 4 33.33 15 3.75±0.94 February 14 3 21.43 14 4.66±1.16 March 11 4 36.36 16 4.00±1.00 April 11 3 27.27 14 4.66±1.16 May 12 2 16.66 16 8.00±2.00 June 11 4 36.36 17 4.25±1.06 July 14 8 57.14 19 2.37±0.59 August 13 5 38.46 18 3.60±0.90 September 14 6 42.86 19 3.16±0.79 October 13 4 30.77 18 4.50±1.13 November 12 6 50.00 14 2.33±0.58 December 12 4 33.33 15 3.75±0.94 Overall 149 53 35.33 195 4.08±1.02 Total 350 226 597 Jan’11-Dec’12 Mean 60.82 3.20 Jan’11-Dec’12

In 2012, the highest prevalence 57.14% and intensity 8.00 ± 2 of infestation was found in July’12 and May’12. The lowest prevalence 16.66% in May’12 and the intensity of parasite was 2.33± 0.58 observed in November’12 (Table-16, 17).

Table 18. Infestation by helminth parasites over the periods 2011 and 2012

P-value Host fish 2011 2012 (using proportion test) W. attu Infected fish (%) 41.13 27.77 0.026* N 124 126

R. rita Infected fish (%) 86.07 35.57 0.000** N 201 149

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 18 shows the result of two sample binomial proportion test. The overall proportion of infected W. attu differs significantly at 5% level of significance between two periods 2011 and 2012. It reveals that the prevalence of infected fish during 2012 (27.77%) was significantly lower than that of 2011 (41.13%) with P < 0.05. Similar trend was shown in case of R. rita. The prevalence differs with strongly statistically significant (P < 0.05) even at 1% level of significance.

In W. attu, the prevalence of trematodes showed the highest prevalence in December’11 (45.45%) and in February’12 (33.33%) in winter season in both the years. The lowest prevalence of infestation was recorded in March’11 (9.09%, in summer) and December’12 (8.33%, in winter). Similarly, the highest intensity recorded 3± 0.75 (January’11, in winter) and 2.5± 0.63 (September’12, in rainy season) while the lowest intensity were (0.5± 0.13 in May’11 and March’12) during summer (Fig- 13).

25 Prevalence (%) 20 Intensity 15

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 13 . Monthly prevalence and intensity of trematode parasites in W. attu

40 Prevalence (%) 30 Intensity 20

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 14. Monthly prevalence and intensity of trematode parasites in R. rita

In R. rita, the maximum prevalence of trematodes was noted as: 75%, in July’11 and 71.43%, in July’12 during rainy season while the minimum prevalence were in April’11, 23.53% and May’12, 25% in summer. The highest intensity were observed (5.2± 1.3, May’11) and (6.3± 1.58, May’12) during summer whereas, the lowest intensity were (0.6± 0.15, October’11) and (0.7± 0.18, July’12) in rainy season for both the years (Fig- 14).

The maximum prevalence of Echinorhynchus kushiroense in W. attu was observed in winter (18.18% in Dec’11) and summer (22.22% in Feb’12) while the minimum prevalence recorded in summer (10% in April’11 and May’12). E. kushiroense in W. attu showed the highest intensity, 2.5± 0.63 in Dec’11(winter) and 3± 0.75 in Feb’12 (summer) [Fig- 15, 16].

Pallisentis ophiocephali showed the maximum prevalence in winter (18.18%, Dec’11) and in summer (22.22%, Feb’12) while in W. attu the minimum prevalence of infestation found in rainy season (9.09%, June’11 and Sep’11) and in winter (8.33%, Dec’12).

P. ophiocephali showed highest intensity (4 ± 0 in June’11 and 4.5± 1.13 in Feb’12) during rainy season and summer respectively and the lowest intensity of P. ophiocephali were (1± 0.25 in Sep’11) rainy season and (Dec’12) winter [Fig- 15, 16].

Along with Acanthocephalus aculeatus, month May’11 (30%) and March’12 (20%) showed highest prevalence of infestation in W. attu in summer. The lowest prevalence were found in Mar’11 (9.09%) and Aug’12 (10%) during summer and rainy season. The maximum (3±0.75, in Aug’12 and 2.5±0.63, in Nov’12) and minimum (1±0.25, in Mar’11 and Aug’11) intensity of A. aculeatus was observed in rainy season, winter and summer respectively (Fig- 15, 16).

E. kushiroense 15 P. ophiocephali A. aculeatus

10 P. umbellatus Prevalence (%) Prevalence

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 15. Monthly prevalence of acanthocephalan parasites in W. attu

4.5

3.5

3 E. kushiroense 2.5 P. ophiocephali

Intensity 2 A. aculeatus P. umbellatus 1.5

0.5

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 16. Monthly intensity of acanthocephalan parasites in W. attu

The highest prevalence of Pallisentis umbellatus in W. attu was recorded 30% (summer, Feb’11) and 25% (winter, Dec’12) for both study year and lowest prevalence of infestation was observed in rainy season (9.09%, June’11 and 10%, July’12). P. umbellatus showed highest intensity (2.33 ± 0.58) in Feb’11 and (3 ± 0.75) in July’12 during summer and rainy season respectively and the lowest intensity of P. umbellatus were (1 ± 0.25 in June’11) rainy season and (0.33 ± 0.08 in Dec’12) winter (Fig- 15, 16).

Maximum prevalence of Cavisoma magnum in R. rita was found during winter, in Nov’11 (17.64%) and rainy season, in July’12 (28.57%). The lowest prevalence (5.26%) was found in winter during Jan’11. The maximum intensity of C. magnum was recorded in summer ( 4 ± 1.00, in Feb’11) and in rainy season ( 3.5 ± 0.88, in July’12) while the minimum intensity ( 1 ± 0.25, in April’11 and May’12) was in summer (Fig- 17, 18).

15 C. magnum C. alaskense

10 C. strumosum Prevalence (%) Prevalence

0 J F M A M J J A S O N D J F M A M J J A S O N D

Fig 17. Monthly prevalence of acanthocephalan parasites in R. rita

4 C. strumosum

C. magnum Intensity 3 C. alaskense

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 18. Monthly intensity of acanthocephalan parasites in R. rita

In R. rita, the prevalence of Corynosoma alaskense showed the highest prevalence during rainy season (23.52%, in June’11 and 21.42% in July’12). The lowest prevalence (5.88%) was observed in Sep’11 (rainy season) and Nov’11 (winter). The highest intensity of C. alaskense was found in rainy season (6.25±1.56, in June’11) and in summer (7±1.75, in May’12) while the lowest intensity (1±0.25) was observed during summer (May’11 and Mar’12) [Fig- 17, 18].

The highest prevalence of Corynosoma strumosum in R. rita was noted as: 12.5%, in July’11 and 14.28%, in July’12 during rainy season while the lowest prevalence was 5.55% in Mar’11 (summer). The maximum intensity of C. strumosum (6±1.50) was in April’11 (summer) and 5.5± 1.38 in July’12 (rainy season) while the minimum intensity (1±0.25) was in rainy season (June’11 and Sep’12) [Fig- 17, 18].

30 Prevalence (%) 20

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 19. Monthly prevalence of parasites in W. attu

In 2011, the prevalence of infestation was highest (72.72%) in December’11 and lowest prevalence (30%) was found in the month of February’11, May’11 and August’11. The highest prevalence (44.44%) found in February’12 & the lowest prevalenc (18.18%) observed in September’12 and November’12 (Fig-19).

2.5

1.5

Intensity 1

0.5

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 20. Monthly intensity of parasites in W. attu

In 2011, the highest intensity of parasites (2.33±0.58) was observed in February’11 and the lowest intensity of parasites (1.33±0.33) was observed in the month of August’11 and October’11.The highest intensity (2.50±0.63) of parasites was in November’12 and the lowest (0.66±0.16) was found in March’12 (Fig- 20).

120

100

60 Prevalence (%) Prevalence 40

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 21. Monthly prevalence of parasites in R. rita

In Jan’11 – Dec’11, the maximum prevalence (100%) was observed in the month of July’11 and the lowest prevalence (73.68%) of infestation was in January’11. In 2012, the highest prevalence (57.14%) was found in July’12 and the lowest prevalence (16.66%) in May’12 (Fig-21). In 2011, the highest intensity (2.75 ± 0.69) of infestation were observed in the month of May’11 and lowest intensity was 2.12 ± 0.53 in September’11. In 2012, the highest intensity (8.00 ± 2.00) of infestation was found in May’12 and the intensity of parasite was lowest (2.33 ± 0.58) observed in November’12 (Fig-22).

4 Intensity 3

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 22. Monthly intensity of parasites in R. rita

In case of W. attu, in 2011, the prevalence of infestation was highest (45.2%) in winter’11 and lowest prevalence (38.1%) was found in summer’11. On the other hand, in 2012, the highest prevalence (30.2%) also found in winter’12 and the lowest prevalence (24.4%) observed in the rainy’12 (Fig-23).

The intensity was highest (2.11 ± 0.53) in winter’11 and lowest intensity (1.49 ± 0.37) was found in rainy’11, while in 2012, the highest intensity (1.66 ± 0.42) also found in winter’12 and the lowest intensity (1.2 ± 0.3) observed in summer’12 (Fig-24).

In case of R. rita, in 2011, the prevalence of infestation was highest (95.4%) in rainy season’11 and lowest prevalence (80.6%) was found in summer’11. On the other hand, in 2012, the highest prevalence (42.6%) also found in the rainy season’12 and the lowest prevalence (28.9%) observed in summer’12 (Fig-25).

The intensity was highest (2.5 ± 0.62) in summer’11 and lowest intensity (2.21 ± 0.55) was found in rainy’11, while in 2012, the highest intensity (5.23 ± 1.3) also found in summer’12 and the lowest intensity (3.41 ± 0.85) observed in the rainy season’12 (Fig-26).

50 45.2 45 40 38.1 40

35 30.2 28.6 30 24.4 25 20

Prevalence (%) 15 10 5 0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12 Seasons

January 2011 - December 2012

Fig 23. Seasonal prevalence of parasites in W. attu during the study period January 2011 to December 2012

2.5 2.11 1.85 2 1.66 1.49 1.54 1.5 1.2

1 Intensity

0.5

0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12

Seasons

January 2011 - December 2012

Fig 24. Seasonal intensity of parasites in W. attu during the study period January 2011 to December 2012

95.4 100 90 82.6 80.6 80

70 60 50 42.6 34 40 28.9 Prevalence (%) 30 20 10 0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12 January 2011 - December 2012

Fig 25. Seasonal prevalence of parasites in R. rita (Jan’11 – Dec’ 12)

6 5.23

4 3.62

3.41

3 2.5

2.21 2.27 Intensity 2

0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12 January 2011 - December 2012

Fig 26. Seasonal intensity of parasites in R. rita (Jan’11 – Dec’ 12)

Table 19. Seasonal association of the infected fishes by helminth parasites

W. attu R. rita

No. of No. of non- P-value No. of No. of non- P-value

infected infected (using chi infected infected (using chi

Seasons fish fish square test) fish fish square test)

2011

Rainy 16 24 62 3

Winter 19 23 0.789 57 12 0.029*

Summer 16 26 54 13

Total 51 73 173 28

2012

Rainy 10 31 23 31

Winter 13 30 0.828 17 33 0.351

Summer 12 30 13 32

Total 35 91 53 96

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 19 shows the “chi square test” providing the association of the number of infected and non-infected fish with different seasons. The R. rita was being infected over the seasons and it was statistically significant (P < 0.05) during 2011. On the other hand, in case of W. attu, there was no association of being infected by the parasites with the seasons during 2011 and 2012.

Table 20. Statistical analysis of infected fishes over seasons

Host fish Seasons No. of infected No. of non-infected P-value (using chi fish fish square test) Rainy 26 55 W. attu Winter 32 53 0.730 Summer 28 56 Rainy 85 34 R. rita Winter 74 45 0.146 Summer 67 45 * Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 20 shows the result of “chi square test”. The infected fish (W. attu and R. rita) was not significantly associated (P > 0.05) with the seasons (rainy, winter and summer) during the study period.

CHAPTER – 4.3

Infestation of parasites in relation to sex of the fishes

Variation of parasite infestation in male and female Wallago attu and Rita rita

The present investigation was done on two species of fish, Wallago attu and Rita rita. Out of 250 W. attu examined, there were 95 male and 155 female. On the other hand, a total of 350 R. rita dissected, there were 210 male and 140 female. In W. attu, the prevalence of Argulus foliaceus in female (25.2%) was higher than male ( 21.6%) and in R. rita, the prevalence of Lernaea cyprinacea in female (36.4%) also higher than male (17.1%) [Table- 21].

Table 21. Prevalence and Intensity of ecto- parasites among W. attu and R. rita according to male and female

Name of the Total no. Total no. Total no. % of Total no. Intensity fish host of host of host of host host of of examined Sex examined infested infested parasites parasites

Wallago attu

(Argulus Male 95 20 21.6 53 2.7± 1.2 foliaceus) 250

Female 155 39 25.2 131 3.4± 1.6

Rita rita 350 Male 210 36 17.1 111 3.1± 1.5

(Lernaea cyprinacea) Female 140 51 36.4 180 3.5± 1.7

Out of 250 W. attu examined, there were 95 male (38%) and 155 female (62%). On the other hand, a total of 350 R. rita dissected, there were 210 male (60%) and 140 female (40%). In W. attu, the prevalence of male (35.8%) was higher than female ( 33.5%) and in R. rita, the prevalence of male (70%) also higher than female (56.4%) [Table-13].

Table 22. Prevalence and Intensity of helminth parasites among W. attu and R. rita according to male and female

Name of Total no. Total no. % of host Total % of Total no. the fish of host of host examined no. of host of host examined Sex examined host infested parasites infested

Wallago Male 95 38 34 35.8 41 attu 250

Female 155 62 52 33.5 103

Rita 350 Male 210 60 147 70 223 rita

Female 140 40 79 56.4 374

Table 23. Association between male and female W. attu and R. rita (through chi square test)

Host fish Sex No. of infected No. of non- Hypothesis P-value fish infected fish (using chi square test)

Male 34 61 H0: There is no W. attu Female 52 103 0.717 association Male 147 63 of infected fish between R. rita Female 79 61 0.009** male and female

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table - 23 shows the “chi square test” whether having association between number of infected fish and sex of the fish. There was strong significant association (P < 0.05) observed between male and female in case of R. rita. However, there was no significant association found in W. attu (P > 0.05).

Monthly prevalence and intensity of ecto-parasite (Argulus foliaceus) in male and female W. attu (Jan’11 - Dec’12)

In the present investigation, the maximum prevalence in males were 100% in Sep’11 and 33.33% in Feb’12 and Oct’12. In female, the highest prevalence were 40% in Nov’11 and 66.66% in Jan’12. There were no ecto-parasites found in male ( Feb’11, April’11, Oct’11, Mar’12, July’12, Sep’12, Nov’12 and Dec’12 respectively) and in female (Jan’11, Feb’11, May’11, June’11 and Oct’11) [Fig – 27].

Table 24. Infestation of male and female W. attu and R. rita by Argulus foliaceus and Lernaea cyprinacea P-value

Host fish Prevalence (%) Prevalence (%) (using proportion

in male in female test)

W. attu 21.05 25.16 0.459

R. rita 17.1 35.0 0.000**

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table - 24 shows the result of “proportion test”. The overall proportion of infected male and female R. rita differs significantly at 5% level of significance during the study period. It reveals that the prevalence of female (35%) was significantly higher (infected by ecto-parasites) than male (17.1%). There was strong association P < 0.05) between male and female in case of R. rita. However, there was no association found in male and female of W. attu ( P > 0.05).

100

In male W. attu, the highest intensity (5 ± 1.25) found in July’11 and (4 ± 1) in Jan’12 while in females, the highest intensity (5 ± 1.25) recorded in July’11 and (6 ± 1.5) in Dec’12. The lowest intensity (2.5 ± 0.62) in male was observed in Nov’11 while in female, the lowest intensity (2 ± 0.5) was found in Jan’12, Feb’12 and Oct’12 (Fig-28).

120

100

60 Male Female

Prevalence (%) Prevalence 40

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 27 . Monthly prevalence of Argulus foliaceus in male and female W. attu

Table 25. Analysis of male and female W. attu and R. rita (infected by Argulus foliaceus and Lernaea cyprinacea) P-value Host fish Male Female (using “t” test) W. attu Mean 2.65 3.36 0.000** SD ±1.18 ±1.56 R. rita Mean 3.08 3.53 0.010** SD ±1.48 ±1.70 * Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

101

Table - 25 shows two sample independent “t –test” for intensity of the parasites between male and female of W. attu and R. rita. The mean difference of the intensity of parasites for W. attu between male and female was strongly statistically significant (P < 0.05). Similar trend was found in case of R. rita. The intensity of parasites differs between male and female was strongly significant (P < 0.05) even at 1% level of significance.

4 Male 3 Intensity Female 2

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 28 . Monthly intensity of Argulus foliaceus in male and female W. attu

Monthly prevalence and intensity of ecto-parasite (Lernaea cyprinacea) in male and female R. rita (Jan’11 - Dec’12)

In the present investigation, the maximum prevalence in males were recorded 44.44% in Dec’11 and 100% in Dec’12. In female, the highest prevalence were 42.85% in Jan’11 and 100% in April’12 and July’12. The lowest prevalence in male were 8.33% in April’11 and 11.11% in Aug’12 and Sep’12 while in female, the lowest prevalence were 14.28% in Aug’11, Dec’11 and 20% in Feb’12 (Fig - 29).

The highest intensity (7 ± 1.75) in males were observed in June’11 and (2.8 ± 0.7) in Feb’12. In female, the highest intensity (5.5 ± 1.37) was found in Sep’11 and Nov’11. The lowest intensity in male (3 ± 0.75) found in Feb’11, July’11, Sep’11 while in female,

102 the lowest intensity (3 ± 0.75) was recorded in Feb’11, Dec’11 and (1 ± 0.25) in Aug’12, Sep’12 (Fig-30).

120

100

60 Male Female

Prevalence (%) Prevalence 40

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 29 . Monthly prevalence of Lernaea cyprinacea in male and female R. rita

4 Male

Intensity 3 Female 2

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 30. Monthly intensity of Lernaea cyprinacea in male and female R. rita

103

Monthly prevalence of helminth parasites in male and female W. attu during Jan’11 - Dec’12

In the present investigation, the maximum prevalence in males were 66.66% in July’11, Sep’11, Dec’11 and Oct’12, Dec’12 respectively. In female, the highest prevalence were 75% in Dec’11 and 50% in Feb’12. The lowest prevalence in male were 20% in Jan’11, Feb’11, June’11, Aug’11, Jan’12 and Mar’12 respectively while in female, the lowest prevalence were 20% in Oct’11 and 12.5% in Nov’12 (Table-26, 27).

Table 26. Monthly prevalence of helminth parasites in male and female W. attu during Jan’11 - Dec’11

Male Female Month No. of No. of Prevalence No. of No. of Prevalence fish fish (%) fish fish (%) examined infected examined infected January 05 01 20 06 03 50 February 05 01 20 05 02 40 March 03 01 33.33 08 04 50 April 05 02 40 05 02 40 May 03 01 33.33 07 02 28.57 June 05 01 20 06 03 50 July 03 02 66.66 07 04 57.14 August 05 01 20 05 02 40 September 03 02 66.66 08 02 25 October 04 02 50 05 01 20 November 05 02 40 05 02 40 December 03 02 66.66 08 06 75 Overall 49 18 39.72 75 33 42.97

104

Table 27. Monthly prevalence of helminth parasites in male and female W. attu during Jan’12 - Dec’12

Male Female

Month No. of No. of Prevalence No. of fish No. of Prevalence fish fish fish (%) examined (%) examined infected infected

January 05 01 20 06 02 33.33

February 03 01 33.33 06 03 50

March 05 01 20 05 02 40

April 05 02 40 06 02 33.33

May 03 01 33.33 07 01 14.28

June 05 02 40 06 01 16.66

July 03 01 33.33 07 01 14.28

August 04 01 25 06 02 33.33

September 04 01 25 07 01 14.28

October 03 02 66.66 07 01 14.28

November 03 01 33.33 08 01 12.5

December 03 02 66.66 09 02 22.22

Overall 46 16 36.39 80 19 24.87

105

Monthly prevalence of helminth parasite in male and female R. rita during Jan’11 – Dec’12

In male R. rita, the highest (100%) prevalence were recorded in July’11, Aug’11 and Nov’12 and the lowest prevalence of male were found in Jan’11, May’11 (66.66%) and 16.66% in May’12. In female R. rita, the highest prevalence 100% were observed in July’11, Sep’11 and Oct’11 respectively and 50% was in Jan’12 while the lowest prevalence 66.66% was found in June’11 and 12.5% in Nov’12 (Table- 28, 29).

Table 28. Monthly prevalence of helminth parasites in male and female R. rita during Jan’11 - Dec’11 Male Female

Month No. of fish No. of fish Prevalence No. of fish No. of fish Prevalence

examined infected (%) examined infected (%)

January 12 08 66.66 07 06 85.71

February 11 10 90.90 06 05 83.33

March 12 09 75 06 05 83.33

April 12 10 83.33 05 04 80

May 06 04 66.66 09 08 88.88

June 11 10 90.90 06 04 66.66

July 10 10 100 06 06 100

August 09 09 100 07 06 85.71

September 11 10 90.90 06 06 100

October 12 11 91.66 04 04 100

November 11 09 81.81 06 05 83.33

December 09 08 88.88 07 06 85.71

Overall 126 108 85.56 75 65 86.88

106

Table 29. Monthly prevalence of helminth parasites in male and female R. rita during Jan’12 - Dec’12

Male Female

Month No. of No. of fish Prevalence No. of No. of Prevalence fish fish fish infected (%) (%) examined examined infected

January 08 02 25 04 02 50

February 09 02 22.22 05 01 20

March 06 03 50 05 01 20

April 07 02 28.57 04 01 25

May 06 01 16.66 06 01 16.66

June 05 03 60 06 01 16.66

July 10 07 70 04 01 25

August 09 04 44.44 04 01 25

September 09 05 55.55 05 01 20

October 06 03 50 07 01 14.28

November 05 05 100 08 01 12.5

December 04 03 75 07 01 14.28

Overall 84 40 49.79 65 13 21.61

Monthly intensity of helminth parasites in male and female W. attu during Jan’11 - Dec’12

In the present investigation, the highest intensity in males were (2 ± 0.5) in Jan’11, Feb’11, May’11, June’11 and Nov’12 respectively. In female, the highest intensity was (3 ± 0.75) in Nov’11, July’12 and Nov’12. The lowest intensity in male was (1 ± 0.25) in

107

Mar’11, April’11, July’11, Aug’11 and Dec’12 respectively while in female, the lowest intensity was (1.5 ± 0.37) in May’11, Aug’11 and 1 ± 0.25 in Mar’12, April’12 and Dec’12 (Fig-31).

3.5

Male 2.5 Female

2 Intensity

1.5

0.5

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 31. Monthly intensity in male and female of W. attu

Monthly intensity of helminth parasites in male and female R. rita during Jan’11 - Dec’12

In the present investigation, the highest intensity in males were (1.5 ± 0.37) observed in May’11 and (7 ± 1.75) in May’12 respectively. In female, the highest intensity was (6 ± 1.5) in April’11 and (10 ± 2.5) in Aug’12. The lowest intensity in male was (1 ± 0.25) found in Feb’11, April’11, Aug’11, Nov’11, Dec’11 respectively and (1.4 ± 0.35) in

108

Nov’12 while in female, the lowest intensity was (3.33 ± 0.83) observed in Sep’11 and

(5.50 ± 1.37) in Jan’12 (Fig-32).

Intensity Female Male 4

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 32. Monthly intensity in male and female of R. rita

Table 30. Statistical analysis of helminth parasites in male and female Wallago attu and Rita rita Host fish Male Female P-value Wallago attu Prevalence (%) 35.8 33.5 0.710* Intensity of 1.20 1.96 0.000** parasites Rita rita Prevalence (%) 70.0 56.4 0.009* Intensity of 1.52 4.73 0.000** parasites *p-value is found using proportion test; ** p-value is found using independent two sample t-test

109

The overall proportion of infected R. rita differs significantly at 5% level of significance between male and female. It reveals that the prevalence of infected male (70%) was significantly higher than female (56.4%) with P < 0.05. However, there was no significant association found between male and female of W. attu ( P > 0.05). However, the mean difference of the intensity of parasites between male and female of W. attu and R. rita was strongly statistically significant ( P < 0.05) during the study period [Table – 30].

Table 31. Analysis of helminth parasites between male and female over the year

W. attu R. rita

P-value P-value (using (using proportion proportion Year Male Female test) Male Female test) N % N % N % N % 2011 0.720 126 85.6 75 86.9 0.797 49 39.7 75 42.9 2012 46 36.4 80 24.9 0.170 84 49.8 65 21.6 0.000** Overall 95 35.8 155 33.6 0.7174 210 70.48 140 55.71 0.005*

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 31 shows the two sample binomial proportion test result. The overall proportion of infected male and female R. rita differs significantly at 5% level of significance between two periods 2011 and 2012. It reveals that the overall prevalence of infected female (55.71%) was significantly lower than male (70.48%). There was strong association (P < 0.05) observed between male and female in case of R. rita. However, there was no significant association found between male and female of W. attu ( P > 0.05).

110

Monthly prevalence and intensity of trematodes in male and female W. attu

In male W. attu, the highest prevalence (33.33%) of trematodes were observed in July’11, Sep’11, Dec’11, Feb’12, May’12, July’12, Nov’12 and Dec’12 respectively and the lowest prevalence (20%) found in Jan’11, April’11, June’11 and April’12. There was no infestation in Feb’11, Mar’11, May’11, Aug’11, Oct’11, Nov’11, Jan’12, Mar’12, June’12, Sep’12 and Oct’12. The highest prevalence (33.33%) of trematodes in female W. attu was found in April’12 and lowest prevalence (11.11%) observed in Dec’12 (Fig-33).

Prevalence of male Prevalence of female

15 Prevalence(%) 10

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 33. Monthly prevalence of trematode parasites in male and female W. attu

In male W. attu, the highest intensity (2 ± 0.5) of trematodes were recorded in Jan’11, April’11, Sep’11, Mar’12, May’12, Nov’12 and Dec’12 and the lowest intensity (1 ± 0.25) found in June’11, July’11, Dec’11, April’12, July’12 and Aug’12 respectively. The female W. attu had the highest intensity (3 ± 0.75) of trematodes in May’11 and lowest intensity (1 ± 0.25) were found in Feb’11, April’11, June’11, July’11, Sep’12, Nov’12 and Dec’12 (Fig-34).

111

Intensity of female Intensity of male 3.5

2.5

Intensity 1.5

0.5

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 34. Monthly intensity of trematode parasites in male and female W. attu

Monthly prevalence and intensity of trematodes in male and female R. rita

In male R. rita, the highest prevalence (80%) of trematodes was observed in Nov’12 and the lowest prevalence (33.33%) found in Mar’11, May’11, Dec’11 and May’12. The highest prevalence (85.71%) of trematodes in female R. rita was found in Aug’11 and lowest prevalence (11.11%) observed in May’11. There was no infestation in Feb’11, April’11, Oct’11, Jan’12 and July’12 (Fig-35).

In male R. rita , the highest intensity (2.5 ± 0.625) of trematodes was recorded in June’12 and the lowest intensity (1 ± 0.25) found in Nov’12. The female R. rita had the highest intensity (5.66 ± 1.41) of trematodes in June’11 and lowest intensity (2 ± 0.5) was found in Sep’12 (Fig-36).

112

Prevalence of female Prevalence of male 90

Prevalence (%) 30

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 35. Monthly prevalence of trematode parasites in male and female R. rita

Intensity of female Intensity of male 6

3 Intensity

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 36. Monthly intensity of trematode parasites in male and female R. rita

113

Monthly prevalence of acanthocephalan parasites in male and female W. attu

In 2011, in case of male W. attu, P. umbellatus showed the highest prevalence (11.11%) in Oct’11 and the lowest prevalence (9.09%) found in A. aculeatus in Mar’11, P. ophiocephali in June’11 and Sep’11 and E. kushiroense in Dec’11. On the other hand, in 2012, A. aculeatus showed the highest prevalence (10%) in male W. attu in Mar’12 and Aug’12 and lowest prevalence (8.33%) observed in P. ophiocephali in Dec’12. There was no infestation in Jan’11, May’11, July’11, Nov’11, Feb’12, April’12, June’12, July’12, Sep’12 and Oct’12 (Fig-37).

In case of female W. attu, in 2011, P. umbellatus showed the highest prevalence (11.11%) in Oct’12 and the lowest prevalence (9.09%) found in June’11. On the other hand, in 2012, the highest prevalence (11.11%) found in E. kushiroense and P. ophiocephali in Feb’12. P. ophiocephali and P. umbellatus showed the lowest prevalence (8.33%) in Dec’12 (Fig- 38).

E. kushiroense 6 P. ophiocephali A. aculeatus Prevalence (%) Prevalence 4 P. umbellatus

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 37. Monthly prevalence of acanthocephalans in male W. attu

114

E. kushiroense 6 P. ophiocephali A. aculeatus

Prevalence (%) 4 P. umbellatus

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 38. Monthly prevalence of acanthocephalans in female W. attu

Monthly prevalence of acanthocephalans in male and female R. rita

In male R. rita, in 2011, the highest prevalence (16.66%) was observed in C. alaskense in May’11 and the lowest prevalence (8.33%) found in C. magnum in Jan’11, April’11 and Oct’11 and in C. alaskense in April’11 and in C. strumosum in Mar’11. On the other hand,

15 C. magnum C. alaskense 10 Prevalence (%) C. strumosum

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 39. Monthly prevalence of acanthocephalans in male R. rita

115

15 C. alaskense C. magnum

Prevalence (%) C. strumosum 10

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 40. Monthly prevalence of acanthocephalans in female R. rita

in 2012, the highest prevalence (16.66%) was found in C. magnum in May’12, in C. alaskense in Mar’12 and May’12 and in C. strumosum in Mar’12. The lowest prevalence (11.11%) observed in C. magnum in Sep’12 and in C. alaskense in Aug’12. There was no infestation in June’12 (Fig-39).

In female R. rita, in 2011, the highest prevalence (16.66%) was recorded in C. alaskense in May’11 and the lowest prevalence (8.33%) found in C. strumosum in Jan’11 and Mar’11. On the other hand, in 2012, the highest intensity (16.66%) found in C. alaskense in Mar’12 and in C. strumosum in Oct’12 and lowest prevalence (11.11%) was found in C. magnum in Sep’12 and in C. alaskense in Aug’12 (Fig-40).

116

CHAPTER – 4.4

Infestation of parasites in relation to length of the fishes

Relationship of ecto-parasites infestation with length of Wallago attu and Rita rita

The present investigation was done on two species of fish, Wallago attu and Rita rita. Out of 250 W. attu, 59 were infected and out of 350 R. rita, 87 were infected with different ecto-parasites. In the present study, W. attu and R. rita were grouped into four length groups. In W. attu, the length groups were 35 – 42 cm, 43 – 50 cm, 51 – 58 cm and 59 – 66 cm. In R. rita, they were 22 – 26 cm, 27 – 31 cm, 32 – 36 cm and 37 – 41 cm.

Table 32. Prevalence and intensity of Argulus foliaceus among four length groups of Wallago attu during Jan’11 - Dec’12 Length No. of fish No. of fish Prevalence of Total no. of Intensity of groups(cm) examined infested infestation parasites parasites (%) collected 35-42 76 24 31.57 75 3.1± 1.5 43-50 73 13 17.80 35 2.7± 1.2 51-58 63 12 19.04 45 3.8± 1.4 59-66 38 10 26.31 29 2.9± 1.7 Total 250 59 23.6 184 3.12± 1.5

2.9 59-66 cm 26.31%

3.75 51-58 cm 19.04% Intensity Prevalence 2.69 43-50 cm Length groups 17.80%

3.12 35-42 cm 31.57%

Fig 41. Prevalence and intensity of Argulus foliaceus in four length groups of W. attu (Jan’11-Dec’12)

117

In W. attu, the maximum prevalence of Argulus foliaceus (31.57%) observed in the smallest length group (35-42 cm) and the minimum prevalence (17.8%) found in 43-50 cm length group. On the other hand, the highest intensity (3.8± 1.4) was recorded in the length group 51 - 58 cm and the lowest intensity (2.7± 1.2) found in 43-50 cm length group (Table-32, Fig- 41).

The infection by ecto-parasite (Argulus foliaceus) was found negatively correlated with length groups (r = -0.41, p = 0.518) which implied that as the length increased, infection tends to decrease.

Table 33. Association between length and infected fish of W. attu (through chi square test)

Length 2011 2012 Overall groups No. of No. of P-value No. of No. of P-value No. of No. of P-value (cm) infected non- (using infected non- (using infected non- (using infected chi infected chi infected chi square square square test) test) test)

35-42 7 30 17 22 24 52 43-50 6 30 7 30 13 60 0.050* 51-58 5 24 0.964 7 26 12 50 0.191

59-66 3 19 7 10 10 29 * Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table - 33 shows the “chi square test” whether having association between number of infected fish with length groups. Infection by ecto-parasite was found to be significantly associated (P < 0.05) with length groups during 2012. However, there was no significant association (P > 0.05) observed in 2011.

118

Table 34. Prevalence and intensity of Lernaea cyprinacea among four length groups of Rita rita during Jan’11 - Dec’12 Length No. of fish No. of fish Prevalence of Total no. of Intensity of groups(cm) examined infested infestation parasites parasites (%) collected 22 - 26 80 20 25 73 3.7± 1.7 27 - 31 79 16 20.2 48 3± 1.5 32 - 36 89 28 31.4 82 2.9± 1.6 37 - 41 102 23 22.5 88 3.8± 1.6 Total 350 87 24.8 291 3.34± 1.6

3.82 37 - 41 cm 22.50%

2.93 32 - 36 cm 31.40% Intensity Prevalence 3

27 - 31 cm 20.20% Length groups

3.65 22 - 26 cm 25%

Fig 42. Prevalence and intensity of Lernaea cyprinacea in four length groups of R. rita (Jan’11-Dec’12)

In R. rita, the maximum prevalence of Lernaea cyprinacea (31.40%) observed in the length group 32 - 36 cm and the minimum prevalence (20.20%) found in 27 - 31 cm length group. On the other hand, the highest intensity (3.8± 1.6) was recorded in the largest length group (37 - 41 cm) and the lowest intensity (2.9± 1.6) found in 32 - 36 cm length group (Table-34, Fig- 42).

The infection by ecto-parasite (Lernaea cyprinacea) was found positively correlated with length groups (r = 0.009, p = 0.868) which implied that as the length increased, infection also tends to increase.

119

Table 35. Association between length and infected fish of R. rita (through chi square test)

Length 2011 2012 Overall groups (cm) No. of No. of P- No. of No. of P- No. of No. of P-value infected non- value infected non- value infected non- (using chi infected (using infected (using infected square chi chi test) square square test) test) 22 - 26 8 36 11 25 19 61 27 - 31 7 35 0.596 8 29 0.181 15 64 0.275 32 - 36 10 39 18 22 28 61 37 - 41 11 55 12 24 23 79

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 35 shows the “chi square test” whether having association between number of infected fish with length groups. The length group was not significantly associated (P > 0.05) with infection by ecto-parasite (Lernaea cyprinacea) in case of R. rita.

Relationship of helminth infestation with length of W. attu and R. rita The present investigation was done on two species of fish, Wallago attu and Rita rita. A total of 250 W. attu, 86 were infected and out of 350 R. rita, 226 were infected with different helminth parasites. In the present study, W. attu and R. rita were grouped into four length groups. In W. attu, the length groups were 35 – 42 cm, 43 – 50 cm, 51 – 58 cm and 59 – 66 cm. In R. rita, they were 22 – 26 cm, 27 – 31 cm, 32 – 36 cm and 37 – 41 cm.

120

1.69 59-66 cm 34.21%

1.82 51-58 cm 26.98%

1.36

Length groups 43-50 cm 26.02%

1.75 35-42 cm 48.68%

Intensity Prevalence

Fig 43. Prevalence and intensity of helminth parasites in four length groups of W. attu (Jan’11 - Dec’12)

In W. attu, the maximum prevalence of helminth parasites infestation was 48.68% in the smallest length group (35-42 cm) and the minimum prevalence (26.02%) found in 43-50 cm length group. The highest intensity (1.82 ± 0.45) was recorded in the length group 51 - 58 cm and the lowest intensity (1.36 ± 0.34) found in 43-50 cm length group (Fig- 43).

In W. attu, during Jan’11 – Dec’11, the maximum prevalence of helminth parasites infestation was 39% in the smallest length group (35-42 cm) and the minimum prevalence (20%) found in 51-58 cm and 59 – 66 cm length group (Table -36, Fig - 44).

121

59-66 cm 20%

35-42 cm 39%

51-58 cm 20%

43-50 cm 21%

Fig 44. Prevalence of helminth parasites in four length groups of W. attu (Jan’11- Dec’11)

On the other hand, in 2012, the highest prevalence (32%) was recorded in the largest length group (59-66 cm) and the lowest prevalence (19%) found in 43-50 cm length group (Table -37, Fig- 45).

Table 36. Prevalence and intensity of helminth parasites among four length groups of Wallago attu during Jan’11 - Dec’11 Length No. of fish No. of fish Prevalence of Total no. of Intensity of groups(cm) examined infested infestation parasites parasites (%) collected 35-42 46 27 58.69 45 1.66 ±0.41 43-50 31 10 32.25 17 1.7 ± 0.42 51-58 37 11 29.73 23 2.09 ± 0.52 59-66 10 03 30.00 10 3.33 ± 0.83 Total 124 51 41.13 95 1.86 ± 0.46

122

59-66 cm 35-42 cm 32% 29%

43-50 cm 51-58 cm 19% 20%

Fig 45. Prevalence of helminth parasites in four length groups of W. attu (Jan’12- Dec’12)

The intensity of helminth parasites in W. attu was lowest (1.66 ± 0.41) in small length group (35-42 cm) and the highest intensity (3.33 ± 0.83) was observed in largest length group (59-66 cm)(Table – 36 and Fig- 46).

Table 37. Prevalence and intensity of helminth parasites among four length groups of Wallago attu during Jan’12 - Dec’12 Length No. of fish No. of fish Prevalence Total no. of Intensity of groups(cm) examined infested of parasites parasites infestation collected (%) 35-42 30 10 33.33 20 2 ± 0.5 43-50 42 09 21.43 09 1 ± 0.25 51-58 26 06 23.07 08 1.33 ± 0.33 59-66 28 10 35.71 12 1.2 ± 0.3 Total 126 35 27.77 49 1.4 ± 0.35

The highest intensity (2 ± 0.5) was observed in the smallest length group (35-42 cm) and the lowest intensity (1 ± 0.25) was found in 43-50 cm length group (Fig- 47 and

123

Table -37). The infection by helminth parasites was found negatively correlated with length groups (r = - 0.105, p = 0.097) which implied that as the length increased, infection tends to decrease.

3.5 3.33 3

2.5

2.09

2 1.66 1.7

1.5 Intensity

0.5

0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 46. Intensity of helminth parasites in four length groups of W. attu (Jan’11-Dec’11)

2.5

2 2

1.5 1.33 1.2 1 Intensity 1

0.5

0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 47. Intensity of helminth parasites in four length groups of W. attu (Jan’12-Dec’12)

124

In R. rita, during the study period, the maximum prevalence of helminth parasites infestation was 73.03% in the length group 32-36 cm and the minimum prevalence (60.70%) found in 27-31 cm length group. On the other hand, The intensity of helminth parasites in R. rita was lowest (2.49 ± 0.62) in the length group 32-36 cm and the highest intensity (2.93 ± 0.73) was observed in the largest (37-41 cm) length group (Fig- 48).

2.93

37-41 cm 61.76%

2.49 32-36 cm 73.03%

2.56

27-31 cm 60.70% Length groups Length

2.54 22-26 cm 62.50%

Intensity Prevalence

Fig 48. Prevalence and intensity of helminth parasites in four length groups of R. rita (Jan’11-Dec’12)

Table 38. Prevalence and intensity of helminth parasites among four length groups of Rita rita during Jan’11 - Dec’11

Length No. of fish No. of fish Prevalence Total no. of Intensity of groups(cm) examined infested of parasites parasites infestation collected (%) 22-26 45 37 82.22 94 2.54 ± 0.63 27-31 51 39 76.47 104 2.66 ± 0.66 32-36 62 59 95.16 141 2.38 ± 0.59 37-41 43 38 88.37 63 1.66 ± 0.41 Total 201 173 86.06 402 2.32 ± 0.58

125

The intensity of helminth parasites in R. rita was lowest (1.66 ± 0.41) in the largest length group (37-41 cm) and the highest intensity (2.66 ± 0.66) was observed in length group (27-31 cm) (Table – 38, Fig- 51).

37-41 cm 22-26 cm 26% 24%

27-31 cm 22% 32-36 cm 28%

Fig 49. Prevalence of helminth parasites in four length groups of R. rita (Jan’11- Dec’11)

22-26 cm 37-41cm 28% 32%

32-36 cm 27-31 cm 16% 24%

Fig 50. Prevalence of helminth parasites in four length groups of R. rita (Jan’12- Dec’12)

126

In R. rita, during Jan’11 – Dec’11, the maximum prevalence of helminth parasites infestation was 28% in the length group (32-36 cm) and the minimum prevalence (22%) found in 27-31 cm length group (Fig- 49). On the other hand, in 2012, the highest prevalence (32%) was recorded in the largest length group (37-41cm) and the lowest prevalence (16%) found in 32-36 cm length group (Fig -50).

Table 39. Prevalence and intensity of helminth parasites among four length groups of Rita rita during Jan’12 - Dec’12

Length No. of fish No. of fish Prevalence Total no. of Intensity of groups(cm) examined infested of parasites parasites infestation collected (%) 22-26 35 13 37.14 33 2.54 ± 0.63 27-31 28 09 32.14 19 2.11 ± 0.52 32-36 27 06 22.22 21 3.5 ± 0.87 37-41 59 25 42.37 122 4.88 ± 1.22 Total 149 53 35.57 195 3.68 ± 0.92

The highest intensity (4.88 ± 1.22) was observed in the largest length group (37-41 cm) and the lowest intensity (2.11 ± 0.53) was found in 27-31 cm length group (Table - 39, Fig- 52). The infection by helminth parasites was found positively correlated with length groups (r = 0.049, p = 0.365) which implied that as the length increased, infection also tends to increase.

127

3 2.66 2.54 2.5 2.38

2 1.66

1.5 Intensity 1

0.5

0 22-26 cm 27-31 cm 32-36 cm 37-41 cm Length groups

Fig 51. Intensity of helminth parasites in four length groups of R. rita (Jan’11-Dec’11)

4.88 5

3.5

3 2.54

Intensity 2.11 2

0 22-26 cm 27-31 cm 32-36 cm 37-41cm Length groups

Fig 52. Intensity of helminth parasites in four length groups of R. rita (Jan’12-Dec’12)

128

In W. attu, the prevalence of I. hypselobagri showed the highest (15.8%) in the smallest length group (35 - 42 cm) and the lowest (2.6%) observed in the largest length group (59 – 66 cm). The prevalence of M. gotoi was recorded highest (8.2%) in 43 – 50 cm length group and lowest (2.6%) in the largest length group (59 – 66 cm). The prevalence of M. trachuri showed the highest (6.3%) in the 51 – 58 cm length group and the lowest (1.4%) found in 43 – 50 cm length group (Fig-53).

Table 40. Association between length and infected fish of W. attu and R. rita by helminth parasites during 2011 and 2012 (through chi square test)

Length W. attu R. rita groups(cm) No. of No. of P-value No. of No. of P-value (using infected non- (using chi infected non- chi square infected square test) infected test) 2011 35-42 27 19 37 8 43-50 10 21 0.025* 39 12 0.030* 51-58 11 26 59 3 59-66 3 7 38 5 2012

35-42 10 20 13 22 43-50 9 33 9 19 51-58 6 20 0.481 6 21 0.324 59-66 10 18 25 34 Overall 35-42 37 39 50 30 43-50 19 54 48 31 51-58 17 46 0.014* 65 24 0.285 59-66 13 25 63 39

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 40 shows the “chi square test” whether having association between number of infected fish of W. attu and R. rita with length groups during 2011 and 2012. The length group was significantly associated (P < 0.05) with infection by

129 helminth parasites in case of W. attu. However, there was no significant association found in R. rita (P > 0.05).

12 10 I. hypselobagri 8 6 M. gotoi M. trachuri

Prevalence (%) Prevalence 4 2 0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 53. Prevalence of trematodes in four length groups of W. attu

The highest intensity (1.3 ± 0.32) of M. gotoi recorded in the smallest length group (35 - 42 cm) and the intensity of M. trachuri showed the highest (2 ± 0) in the smallest length group (35 - 42 cm) [Fig-54].

2.5

1.5 I. hypselobagri M. gotoi Intensity 1 M. trachuri

0.5

0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 54. Intensity of trematodes in four length groups of W. attu

130

In R. rita, the prevalence of N. leiognathi showed the highest (22.5%) in the smallest length group (22 – 26 cm) and the lowest (14.6%) observed in the 32 – 36 cm length group. The prevalence of S. obesum was recorded highest (25.8%) in 32 – 36 cm length group and lowest (12.6%) in 27 – 31 cm length group.

The highest prevalence (17.7%) of S. musculus observed in 27 – 31 cm length group and lowest (12.5%) found in the smallest length group (22 – 26 cm). The maximum prevalence (18.7%) of C. piscidium found in the smallest length group (22 – 26 cm) and the minimum prevalence (7.6%) recorded in 27 – 31 cm length group (Fig - 55).

22-26 cm 15 27-31 cm 32-36 cm

Prevalence (%) Prevalence 37-41 cm 10

0 N. leiognathi S. obesum S. musculus C. piscidium

Fig 55. Prevalence of trematodes in four length groups of R. rita

131

1.8

1.6

1.4

1.2 22-26 cm 27-31 cm 1 32-36 cm

Intensity 0.8 37-41 cm

0.6

0.4

0.2

0 N. leiognathi S. obesum S. musculus C. piscidium

Fig 56. Intensity of trematodes in four length groups of R. rita

Similarly, the intensity of N. leiognathi showed the highest (1.8 ± 0.45) in the smallest length group (22 – 26 cm) and the lowest (1.3 ± 0.32) observed in 32 – 36 cm length group. The intensity of S. obesum was recorded highest (1.9 ± 0.47) in the largest length group (37 – 41 cm) and lowest (1 ± 0) in 27 – 31 cm length group.

The highest intensity (1.4 ± 0.35) of S. musculus observed in the smallest length group (22 – 26 cm) and lowest (1.1 ± 0.2) found in the largest length group (37 – 41 cm). The maximum intensity (1.8 ± 0.45) of C. piscidium found in 27 – 31 cm length group and the minimum intensity (1.2 ± 0.3) recorded in 32 – 36 cm length group (Fig - 56).

In W. attu, the prevalence of Polyoncobothrium polypteri showed the highest (4.76%) in 51 - 58 cm length group and the lowest (2.63%) observed in the smallest (35 – 42 cm) length group (Fig-57).

The intensity (1 ± 0) of Polyoncobothrium polypteri was recorded in the smallest (35 – 42 cm) length group and 51 - 58 cm length group (Fig - 58).

132

5 4.5

3.5 3 2.5 2

1.5 Prevalence (%) 1 0.5 0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 57. Prevalence of Polyoncobothrium polypteri in four length groups of W. attu

1 0.9 0.8

0.7

0.6 0.5

0.4 Intensity 0.3 0.2 0.1 0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 58. Intensity of Polyoncobothrium polypteri in four length groups of W. attu

In W. attu, the prevalence of C. aguirrei showed the highest (5.3%) in the largest length group (59 – 66 cm) and the lowest (2.7%) observed in 43 – 50 cm length group.

The highest prevalence (7.9%) of Contracaecum L3 larva recorded in the smallest length group (35 – 42 cm) and lowest (1.4%) found in 43 – 50 cm length group (Fig-59).

133

59-66 cm

51-58 cm

Contracaecum L3 larva C. aguirrei

43-50 cm Length groups Length

35-42 cm

0 2 4 6 8 Prevalence (%)

Fig 59. Prevalence of nematodes in four length groups of W. attu

Similarly, the intensity of C. aguirrei showed the highest (1.6 ± 0.4) in the smallest length group (35 – 42 cm) and the highest intensity (1.3 ± 0.32) of Contracaecum L3 larva also recorded in the smallest length group (35 – 42 cm) [Fig-60].

1.6 1.4

1.2

1 0.8 C. aguirrei 0.6 Intensity Contracaecum L3 larva 0.4 0.2 0 35-42 cm 43-50 cm 51-58 cm 59-66 cm Length groups

Fig 60. Intensity of nematodes in four length groups of W. attu

134

Prevalence(%) 4

0 22-26 cm 27-31 cm 32-36 cm 37-41 cm Length groups

Fig 61. Prevalence of nematodes in four length groups of R. rita

37-41 cm

32-36 cm

27-31 cm Length groups Length

22-26 cm

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Intensity

Fig 62. Intensity of nematodes in four length groups of R. rita

135

In R. rita, the prevalence of Ascaroid larva showed the highest (10.1%) in 32 – 36 cm length group and the lowest (7.6%) observed in 27 – 31 cm length group (Fig- 61).

The highest intensity (1.8 ± 0.45) of Ascaroid larva recorded in 27 – 31 cm length group and lowest (1.3 ± 0.3) found in the smallest length group (22 – 26 cm) [Fig-62].

12.00

10.00

8.00 35-42 cm 6.00 43-50 cm 51-58 cm 4.00 Prevalence (%) Prevalence 59-66 cm

2.00

0.00 E. kushiroense P. ophiocephali A. aculeatus P. umbellatus

Fig 63. Prevalence of acanthocephalans in four length groups of W. attu

3.5

2.5 35-42 cm 43-50 cm 2 51-58 cm

Intensity 1.5 59-66 cm

0.5

0 E. kushiroense P. ophiocephali A. aculeatus P. umbellatus

Fig 64. Intensity of acanthocephalans in four length groups of W. attu

136

In W. attu, the prevalence of Echinorhynchus kushiroense showed the highest (2.73%) in 43 – 50 cm length group and the lowest (1.58%) observed in the 51 – 58 cm length group. The prevalence of P. ophiocephali was recorded highest (6.57%) in the smallest length group (35 – 42 cm) and lowest (1.36%) in 43 – 50 cm length group.

The highest prevalence (5.26%) of A. aculeatus observed in the smallest length group (35 – 42 cm) and lowest (3.17%) found in 51 – 58 cm length group. The maximum prevalence (10.5%) of P. umbellatus found in the largest length group (59 – 66 cm) and the minimum prevalence (1.36%) recorded in 43 – 50 cm length group (Fig - 63).

In W. attu, the intensity of Echinorhynchus kushiroense showed the highest (3 ± 0.7) in the largest length group (59 – 66 cm) and the lowest (1 ± 0) observed in 51 – 58 cm length group. The intensity of P. ophiocephali was recorded highest (4 ± 0) in 51 – 58 cm length group and lowest (2 ± 0) in the largest length group (59 – 66 cm). The highest intensity (2 ± 0) of A. aculeatus observed in 51 – 58 cm length group and lowest (1 ± 0) found in the largest length group (59 – 66 cm). The maximum intensity (3 ± 0.7) of P. umbellatus found in 51 – 58 cm length group and the minimum intensity (1.2 ± 0.3) recorded in the smallest (35 – 42 cm) length group (Fig - 64).

37-41 cm

32-36 cm

C. strumosum C. alaskense 27-31 cm Length Length groups C. magnum

22-26 cm

0 2 4 6 8 10 12 14 16 18 Prevalence (%)

Fig 65. Prevalence of acanthocephalans in four length groups of R. rita

137

2.5

1.5

Intensity 1 C. magnum C. alaskense 0.5 C. strumosum

0 22-26 cm 27-31 cm 32-36 cm 37-41 cm Length groups

Fig 66. Intensity of acanthocephalans in four length groups of R. rita

In R. rita, the prevalence of C. magnum showed the highest (13.48%) in 32 – 36 cm length group and the lowest (6.32%) observed in 27 – 31 cm length group. The prevalence of C. alaskense was recorded highest (13.72%) in the largest length group (37 – 41 cm) and lowest (6.25%) in the smallest length group (22 – 26 cm). The highest prevalence (11.25%) of C. strumosum observed in the smallest length group (22 – 26 cm) and lowest (7.59%) found in 27 – 31 cm length group (Fig - 65).

In R. rita, the intensity of C. magnum showed the highest (1.6 ± 0.4) in the largest length group (37 – 41 cm) and the lowest (1.1 ± 0.2) observed in 32 – 36 cm length group. The intensity of C. alaskense was recorded highest (2.1 ± 0.5 ) in the largest length group (37 – 41 cm) and lowest (1.6 ± 0.4) in the smallest length group (22 – 26 cm). The highest intensity (1.6 ± 0.4) of C. strumosum observed in 27 – 31 cm length group and lowest (1.3 ± 0.3) found in the smallest (22 – 26 cm) length group (Fig - 66).

138

CHAPTER – 4.5

Infestation of parasites in relation to climatic factors

Climatic factors The environmental factors including climate, season and rainfall play an important role in the development of helminth parasites. Climate change may directly affect fishery production along many pathways. Fish reproduction, growth and migration patterns are all affected by temperature, rainfall and hydrology (Ficke et al. 2007). Knowledge of the biology of the parasite and its host(s), the host– parasite relationship and the environment can help to detect environmental change.

160 148 mm

140

120 110 mm

100

80 2011 70 70 2012

60 Value of parameters of Value 41.13 % 40 25.8 26.1 27.77% 20 1.84 1.4 0 Temperature(◦c) Humidity(%) Rainfall(mm) Prevalence Intensity

Fig 67. Difference in temperature, humidity, rainfall, prevalence and intensity of parasites of W. attu in 2011 and 2012

In Wallago attu, the observed values of temperature, humidity, rainfall, prevalence and intensity were 25.8 ◦ C, 70%, 148 mm, 41.13% and 1.84 respectively in the year of 2011. On the other hand, in 2012, the recorded values were temperature – 26.1 ◦ C, humidity – 70%, rainfall – 110 mm, prevalence – 27.77% and intensity – 1.4 (Fig - 67).

139

160 148 mm

140

120

110 mm

100 86.32 %

80 70 70 2011 2012

60 Value Value parameters of

40 35.33 % 25.8 26.1 20 2.33 4.08 0 Temperature(◦c) Humidity(%) Rainfall(mm) Prevalence Intensity

Fig 68. Difference in temperature, humidity, rainfall, prevalence and intensity of parasites of R. rita in 2011 and 2012

In Rita rita, the observed values of temperature, humidity, rainfall, prevalence and intensity were 25.8 ◦ C, 70%, 148 mm, 86.32% and 2.33 respectively in the year of 2011. On the other hand, in 2012, the recorded values were temperature – 26.1 ◦ C, humidity – 70%, rainfall – 110 mm, prevalence – 35.33% and intensity – 4.08 (Fig - 68).

Temperature

Parasitic worms that infect fish, and have a devastating effect on fish reproduction, grow four times faster at higher temperatures -- providing some of the first evidence that global warming affects the interactions between parasites and their hosts. In Rita rita, the highest temperature (28.72 ◦ C and 28.8 ◦ C) and highest prevalence (95.4% and 42.6%) were recorded during rainy season in 2011 and 2012 both. The lowest average temperature (20.75 ◦ C and 20.72 ◦ C) was recorded during winter in 2011 and 2012 while the lowest prevalence (80.6% and 28.9%) was observed during summer in 2011 and 2012. The prevalence was found negatively correlated with temperatures (r = - 0.53) [Fig – 69].

140

120

100

95.4 80 82.6 80.6

60 Prevalence % 42.6 Temperature ◦c 34 40 28.9

20 28.72 27.97 28.8 28.75 20.75 20.72

0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12

Fig 69. Prevalence of parasites of R. rita in different seasons according to temperature

50 45.2 45 40 40 38.1

35 30.2 28.72 28.8 28.75 30 27.97

25 20.75 20.72 28.6

20 24.4 Prevalence % 15 Temperature ◦c 10

0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12

Fig 70. Prevalence of parasites of W. attu in different seasons according to temperature

141

In W. attu, in 2011 and 2012 , the highest temperature (28.72 ◦ C and 28.8 ◦ C) were recorded during rainy season and the highest prevalence (45.2% and 30.2%) were found during winter. The lowest temperature (20.75 ◦ C and 20.72 ◦ C) was recorded during winter in 2011 and 2012 while the lowest prevalence (38.1%) was observed during summer in 2011 and 24.4% during rainy season in 2012. The prevalence was negatively correlated with temperatures (r = - 0.49) [Fig – 70].

120

100

60 Temperature(◦c)

40 Prevalence(%)

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 71. Prevalence of parasites of R. rita in different months according to temperature

In Rita rita, in 2011 , the highest temperature (36.2 ◦ C) were observed in the month of Sep’11 and lowest temperature was 27.8 ◦ C in Jan’11 while the highest prevalence (100%) were observed in the month of July’11 and lowest prevalence was 73.68% in Jan’11. In 2012, the highest temperature (37.3 ◦ C) was found in Mar’12 and lowest (28.5 ◦ C) observed in Dec’12 and Jan’12 while the highest prevalence (57.14%) recorded in July’12 and lowest was 16.66% in May’12. The prevalence was positively correlated with temperatures (r = 0.65) in different months (Fig – 71).

142

40 Temperature(◦c) 30 Prevalence(%)

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 72. Prevalence of parasites of W. attu in different months according to temperature

Table 41. Association between temperature and infected fish of W. attu and R. rita (through chi square test) W. attu R. rita

No. of No. of P-value No. of No. of P-value Temperature infected non- (using chi infected non- (using chi (◦ C) infected square test) infected square test) <31.0 19 26 36 23 31.0-34.4 18 42 0.317 50 37 0.000** 34.5-36 31 50 105 23 >36 18 46 35 41

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table - 41 shows the “chi square test” whether having association between number of infected fish of W. attu and R. rita with temperatures. There was strong significant association (P < 0.05) observed in case of R. rita. However, there was no significant association found in W. attu (P > 0.05).

143

In Wallago attu, in 2011 , the highest temperature (36.2 ◦ C) were observed in the month of Sep’11 and lowest temperature was 27.8 ◦ C in Jan’11 while the highest prevalence (72.72%) were observed in the month of Dec’11 and the lowest prevalence was 30% in Feb’11, May’11 and Aug’11. In 2012, the highest temperature (37.3 ◦ C) was found in Mar’12 and lowest (28.5 ◦ C) observed in Dec’12 and Jan’12 while the highest prevalence (44.44%) recorded in Feb’12 and the lowest was 18.18% in Sep’12 and Nov’12. The prevalence was positively correlated with temperatures (r = 0.66) in different months (Fig – 72).

Rainfall

Seasonality of rainfall can exert a strong influence on animal condition and on host- parasite interactions. The body condition of ruminants fluctuates seasonally in response to changes in energy requirements, foraging patterns and resource availability, and seasonal variation in parasite infections may further alter ruminant body condition.

In Rita rita, in 2011 , the highest rainfall (94 mm) were observed in the month of Aug’11 and lowest rainfall was 14 mm in Mar’11 while the highest prevalence (100%) were observed in the month of July’11 and lowest prevalence was 73.68% in Jan’11. In 2012, the highest rainfall (62 mm) was found in April’12 and lowest (1) observed in Feb’12 while the highest prevalence (57.14%) recorded in July’12 and lowest was 16.66% in May’12. The prevalence was positively correlated with rainfall (r = 0.67) in different months (Fig – 73).

In Rita rita, the highest rainfall (271 mm and 156.75 mm ) and highest prevalence (95.4% and 42.6%) were recorded during rainy season in 2011 and 2012 both. The lowest rainfall ( 0 mm and 21 mm) was recorded during winter in 2011 and 2012 while the lowest prevalence (80.6% and 28.9%) was observed during summer in 2011 and 2012 (Fig – 74).

144

120

100

60 Rainfall (mm) Prevalence(%) 40

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 73. Prevalence of parasites of R. rita in different months according to rainfall

In Wallago attu, in 2011 , the highest rainfall (94 mm) were observed in the month of Aug’11 and lowest rainfall was 14 mm in Mar’11 while the highest prevalence (72.72%) were observed in the month of Dec’11 and the lowest prevalence was 30% in Feb’11, May’11 and Aug’11. In 2012, the highest rainfall (62 mm) was found in April’12 and lowest (1 mm) observed in Feb’12 while the highest prevalence (44.44%) recorded in Feb’12 and the lowest was 18.18% in Sep’12 and Nov’12. The prevalence was positively correlated with rainfall (r = 0.57) in different months (Fig – 75).

145

300 271 mm

250

200 173 mm 156.75 mm 154.5 mm 150 Prevalence % Total rainfall 100 95.4 82.6 80.6 50 34 42.6 0 mm 21 mm 28.9 0 Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12

Fig 74. Prevalence of parasites of R. rita in different seasons according to rainfall

100

50 Rainfall (mm) 40 Prevalence(%) 30

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 75. Prevalence of parasites of W. attu in different months according to rainfall

146

300 271 mm

250

200 173 mm 156.75 mm 154.5 mm 150 Prevalence % Total rainfall

100

40 45.2 50 38.1 24.4 30.2 28.6 0 0 21 mm Rainy’11 Winter’11 Summer’11 Rainy’12 Winter’12 Summer’12

Fig 76. Prevalence of parasites of W. attu in different seasons according to rainfall

Table 42. Association between rainfall and infected fish of W. attu and R. rita (through chi square test)

W. attu R. rita

No. of No. of P-value No. of No. of non- P-value Rainfall infected non- (using chi infected infected (using chi (mm) infected square test) square test) <13 30 44 68 39 13-25 15 38 42 30 26-53 18 42 0.432 59 28 0.558 >53 23 40 57 27

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

Table – 42 shows the “chi square test” whether having association between number of infected fish of W. attu and R. rita with raifall. The rainfall was not significantly associated (P > 0.05) with infection by helminth parasites in both the fishes.

147

Humidity

In Rita rita, in 2011 , the highest humidity (99%) were observed in the month of Jan’11 and lowest humidity was 93% in Feb’11, Mar’11 and April’11 while the highest prevalence (100%) were observed in the month of July’11 and lowest prevalence was 73.68% in Jan’11. In 2012, the highest humidity (100%) was found in July’12 and lowest (92%) observed in Feb’12 while the highest prevalence (57.14%) recorded in July’12 and lowest was 16.66% in May’12. The prevalence was positively correlated with humidity (r = 0.51) in different months (Fig – 77).

120

100

60 Humidity (%) 40 Prevalence (%)

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 77. Prevalence of parasites of R. rita in different months according to humidity

148

180

160

140

120

100

80 Prevalence(%)

60 Humidity (%)

0 J F M A M J J A S O N D J F M A M J J A S O N D

January 2011 - December 2012

Fig 78. Prevalence of parasites of W. attu in different months according to humidity

Table 43. Association between humidity and infected fish of W. attu and R. rita (through chi square test)

W. attu R. rita

No. of No. of P-value No. of No. of P-value

infected non- (using chi infected non- (using chi Humidity infected square infected square test) (%) test) 92-94 21 40 52 37 95-97 53 92 0.525 142 60 0.028** 98-100 12 32 32 27

* Significant, ** highly significant, P < 0.05; ns = not significant at 5% level, P > 0.05

149

Table – 43 shows the “chi square test” whether having association between number of infected fish of W. attu and R. rita with humidity. The humidity was found to be significantly associated (P < 0.05) with infection by helminth parasites in R. rita.

150

CHAPTER – 4.6

Infestation in relation to the food and feeding habits of the host fishes

Analysis of food items in the stomach of Wallago attu and Rita rita

The study of the food and feeding habit is useful and fundamental to understand the functional role of the fish within its ecosystems. It has importance in fishery biology and the subject has been extensively studied in the recent decades. A detail knowledge on the food and feeding habit of fishes provide keys for the selection of culturable species and the importance of such information for successful fish farming.

The main purpose of the study on food items in the fish was to confirm the expected relation between fish diet and parasite occurrence in W. attu and R. rita. Little is known about the fish parasites and their correlation with the occurrence of specific type of food items.

A total of 250 stomachs of W. attu and 350 stomachs of R. rita were examined from January 2011 to December 2012, to find out the food components in their diet. Attempts were made to determine the percentage of frequency of occurrence of the food items in relation to the total number of stomachs examined in each month of the study period in each species of fish. Attempts were also made to find the “most important food” or “main food” items with consideration to the views of Guziur (1976) and accordingly the food items were distinguished into three kinds (Table- 44):

a) Main food- the animal components that comprise the greatest proportion of the fish diet and was been designated as “main food”; b) “the additional food”- the animal foods consumed by 5 - 35% of the fishes; and c) “the incidental food”- the animal and plant components found in less than 5% of all fish examined.

The food items found in stomachs of fishes, were determined by “Occurrence Method” (Frost 1946, 1954; Hynes 1950; Hunt and Carbine 1951) where the number of fish stomach in which each food item occurred was listed and expressed as a percentage of total number of stomachs examined.

151

Plate No. 3

Fig.Food items collected from the stomach of W. attu andR. rita

152

Table 44. Frequency of occurrence and the significance of particular components in the food of W. attu and R. rita

Kind Significance Food components Occurrence in Occurrence W. attu in R. rita Fish: Amblyphryngodon mola, Botia sp., Corica sp., fish scales, eggs, bones, 27.2 18.3 eye balls, fins, operculum, head, Main food barbells. Crustaceans: Prawns, small crabs, copepods (Cyclops, Diaptomas), 17.6 4.8 ostracodes (Cypris), Animal food crustacean larva and appendages Molluscans: Gastropods (Limnaea, Amnicola) 3.2 18 and Bivalvia (shells and mantles of Pila, Additional food Unio etc.) Insects: Coleoptera, Cladocera, Diptera, 5.2 3.1 Lepidoptera, nymphs of dragon flies, mosquito larvae. Macrophytes, algae, Plant food Incidental food seed, diatoms, root and stem of aquatic 6 3.7 plants, aquatic grass, debris, muds

The food items found in the stomach of W. attu and R. rita were divided into five basic categories: fish, crustaceans, insects, molluscans and plants. The fishes also consumed macrophytes, mud and sand to a smaller extent. A good percentage of empty stomachs were also observed in both the fish species.

153

Plant food, 6% Molluscans, 3.20% Fish , 27.20%

Crustaceans, 17.60%

Insects, 5.20%

Fig 79. Percentage of different food items found in the stomach of W. attu

Plant food, 3.70% Fish , 18.30%

Crustaceans, 4.80%

Molluscans, 18%

Insects, 3.10%

Fig 80. Percentage of different food items found in the stomach of R. rita

154

Main food items:

(1) Small fishes:

Among the components of animal food, the most important and most frequent were the small fishes which comprised the greatest proportion of the diet (Fig-79, 80) of W. attu and R. rita. The majority of fishes in stomach were Amblyphryngodon mola, Botia sp., Corica sp. This category of food also contained considerable number of fish fry, fish scales, eggs, bones, eye balls, fins, operculum, head, barbells. The frequency of occurrence of small fishes were 27.2% in W. attu and 18.3% in R. rita (Table - 44).

The seasonal variation of frequency of occurrence of small fish food item followed almost similar pattern in both the host fishes. In W. attu, the highest occurrence was

30 W. Attu R. Rita

20 Occurrence (%) Occurrence

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 81. Monthly occurrence of small fish food item in stomach of W. attu and R. Rita evident in August 2011 (50%) and October 2012 (44.4%), lower consumption was in winter months (Nov’11 and Jan’12). In R. rita, the peaks were prominent in October 2011 (31.2%) and April 2012 (36.4%), lower frequency was observed during the months of January (2011) and September (2012) [Fig-81].

155

(2) Crustacea:

Crustaceans were the most abundantly consumed group of animal food including larvae and adults and they filled a significant proportion of the stomachs in all the months of the study period. This item consisted of prawns, small crabs, copepods (Cyclops, Diaptomas), ostracodes (Cypris), crustacean larva and appendages etc. Other copepods were also prevalent.

30 W. Attu R. Rita

20 Occurrence (%) Occurrence

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 82. Monthly occurrence of crustacea food item in stomach of W. attu and R. rita

The frequency of occurrence of crustacea were recorded 17.6% in W. attu and 4.8% in R. rita (Table- 44 ). The seasonal and monthly variation of frequency of crustaceans in W. attu and R. rita are shown in Fig-82. In W. attu, in both the years, there was a similar sequential pattern in the peaks of the frequency curves. The peaks were evident during March (36.4%, 2011 and 50%, 2012) and lower consumption was 10% (May’11 and Nov’11) and 9.1% (June’12 and Nov’12). In R. rita, the peaks were prominent in August 2011 (12.5%) and lower frequency (5.8%) was observed during the month of February 2011[Fig-82].

156

Additional food items:

(1) Insects:

Among the additional food items consumed by W. attu and R. rita, the aquatic insects were the representatives of Coleoptera, Cladocera, Diptera, Lepidoptera etc. This group of animals were most frequent and abundant in stomachs (Table- 44).

10 W. Attu

8 R. Rita Occurrence (%) Occurrence 6

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 83. Monthly occurrence of insect food item in stomach of W. attu and R. rita

In W. attu, the frequency of occurrence of insects was 5.2% and in R. rita, it prevailed 3.1%. The occurrence did not follow any seasonal pattern in both the hosts and showed little differences in month to month during the period. The maximum frequency of occurrence was recorded 18.2% (June 2011) in W. attu and 9.1% (April, June 2012) in R. rita (Fig-83).

157

(2) Mollusca:

Mollusca were consumed by 3.2% of W. attu and 18% of R. rita examined. The representatives were Gastropods (Limnaea, Amnicola) and Bivalvia (shells and mantles of Pila, Unio).

20 W. Attu R. Rita

15 Occurrence (%) Occurrence

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 84. Monthly occurrence of molluscan food item in stomach of W. attu and R. rita

In W. attu, sharp increase in consumption (10%) occurred in May’11 and August 2012. In R. rita, the peaks (27.7% and 36.4%) were observed in March for both the years and lower frequency (6.2%) was observed during the months of July 2011 and 8.3% in November 2012 [Fig-84].

158

Incidental food items:

Plants:

The food of plant origin contained macrophytes, algae, seed, diatoms, root and stem of aquatic plants, aquatic grass, debris, muds etc. Among the algae, Spirogyra sp. and Oscillatoria sp. were common. The frequency of consumption of plant food item (Table- 44) was higher in W. attu (6%) than in R. rita (3.7%).

R. Rita

10 W. Attu Occurrence (%) Occurrence

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 85. Monthly occurrence of plant food item in stomach of W. attu and R. rita

In W. attu, in both the years, there was a similar sequential pattern in the peaks of the frequency curves. The peaks were evident during winter months (18.2% in Jan’11 and 11.1% in Feb’12) and lower consumption was 8.3% (Dec’12). In R. rita, the peaks (9.1%) were prominent in 2012 (March and April) and lower frequency (5.3%) was observed during the months of January 2011 [Fig-85].

159

CHAPTER – 5

PATHOLOGICAL EFFECTS OF THE PARASITES

Histopathological effects of helminths in different organs of Wallago attu and Rita rita

Parasite causes damage to their host and they occupy a definite position or site in suitable environment on their hosts. Fishes are one of the most common hosts of helminth parasites. The parasites of digestive tract feed either on the digested contents of the host’s intestine or the host’s own tissues (Markov, 1946). The influence of the parasite may result in extensive change in individual organs or tissues or it can exert a general effect on host. “Like all animals, fishes have their full compliment of disease and parasites and of abnormalities, both malignant and benign and there is no question that most fishes die from such disorders, natural enemies other than men”(Lagler, 1956).

The helminth parasites usually cause the damage in the surrounding of their microhabitat into the host body. This damage occurs when the parasites pierce the various organs of digestive system for having their food from the host’s body; their migration causes disturbances to the host’s multiple systems, the cluster of parasite block the channel of fluid in the host body, heavy infection causes deficiency of hosts nutrition, lesions, ulcer and finally the death of the host.

In the present observation, multiple organs were examined to find out the mode of parasites present in the body of W. attu and R. rita. Some histological and pathological changes were observed on the skin, body musculature, swim bladder and visceral organs of the host fishes. Structural integrity of the skin, body musculature and visceral organs were more disrupted by the juvenile trematode Isoparorchis hypselobagri and Contracaecum sp. larvae than other helminth parasites which were found in the stomach and intestine.

In the present study, Isoparorchis hypselobagri and Contracaecum sp. larvae were found to be the most pathogenic and damaging one [Plate – 4 (B, C)]. As no report on the study of the pathological effects of these parasites in these host fishes are available, the nature and degree of pathogenicity were chosen for this particular study.

160

Histopathological studies showed that skin, muscle layer, swim bladder, intestine, lower part of intestine, liver and kidney were damaged by the infestation of helminth parasites. Skin, muscles, intestine, liver, kidney tissues were found to be more infected and in future these infected organs causes severe problem in the growth of fish. Some parasites were deeply attached to the host muscle caused cell damage as well as partly destroyed the organs function. While, some were free and only live on hosts nutrients. These free parasites present in the lumen thus the diameter of the intestine become narrower and the system faced hamper.

In the present study, stomach and intestine were infected by trematode, cestode, nematode and acanthocephalan parasites. In the histopathological examination, at the site of attachment of cyst to the intestinal wall of the host, mechanical displacement and compression of tissue layer, especially muscularis were noticed. The muscularis mucosa were fully disrupted and damaged by the parasites.

Description of the damages occurred due to parasitic infestation:

Infections in body cavity are supposed to cause visceral adhesions that impair the functions of intestinal tract by interfering with the parasites. However, the mechanical obstruction was caused due to the occurrence of the parasites in clusters. The pathology manifested in the form of compression of the muscular folds was due to multiple infections.

Helminth parasites generally affect the internal organs of the host fish, particularly the gut. They perforate the intestine heavily and inhibit host’s growth. The normal growth of fishes is interrupted and inhibited if they are heavily infested with endoparasites viz., trematode, nematode, cestode and acanthocephalan. The irritating activities and damage of tissues lining the walls of the oesophagus, stomach, intestine etc. cause microscopic lesions in their host’s tissues which become the site for the secondary infection by bacteria (Cheng, 1964). Each true fish parasite therefore uses the fish for its home and food and the total damage is related to the numbers of parasites present (Soulsby, 1968; Hoffman, 1967).

161

Plate No. 4

A. Incision through the midventral line of the body of W. attu. B. Free juvenile trematode I. hypselobagri found in the swim bladder of W. attu. Juvenile I. hypselobagri are able to destroy the muscle tissue (of the particular region) and feed on it. Large empty spaces with fragmented blood capillaries, debris of tissues and tissue fluid are found around the parasite. C. Free nematodes (larval forms) coming out from the visceral cavity of W. attu.

162

Plate No. 4

Isoparorchis hypselobagri

Nematodes (larval forms)

163

Helminths are very common in freshwater fishes. Very few lesions have been attributed to intestinal forms. Histozoic helminthes particularly migrating forms, cause greater damage in fishes. In severe cases, hyperemia, hemorrhage, cellular infiltration, lesion, nacrosis, fibrosis etc. have been observed. After encystment and fibrotic encapsulation, many larval helminthes produce no further obvious damage except pressure on adjacent host tissue. Migrating larva of trematode (cercariae), cestode (plurocercoides) and nematode produce the most serious reactions: leukocytes, fibrosis, hemorrhage and necrosis. Continual migrations, such as larvae of Contracaecum sp. produce peritonitis which results in fibrosis and extensive adhesions. Rapid invasion by large number of cercariae produce extensive hemorrhage, hyperemia, necrosis and even

death if present in sufficient numbers.

Many fishes were observed with marks of perforation, lacerations and scars on their surface and abdomen. It is assumed that many metacercarial forms might be lost through these laceration processes. Any kind of internal changes or due to the cause of host’s death, metacercarial forms need to leave the host immediately. At that time they bored their way in to the external environment for their survival through laceration processes. Sometimes, it was also observed during the study period that, the trematode reaches the buccal cavity or gill and sometimes came out through the anus or genital opening of lower abdomen.

Cestodes were found to have different habits and distribution pattern to the various organs of the hosts. Some of them were attached by mean of scolex and a very few number was found to exposed freely in the gut. Most of the Caryophyllaeid cestodes shows its abundance in the first and second loop of anterior part of the intestine, immediately behind the stomach which also agreed with Mackiewcz (1972). He also predicted that the normal distribution patterns of many species may be altered in the case of heavy infections.

In the stomach and intestine, the scolex of the mature form of Polyoncobothrium polypteri was embedded within the muscularis and the rest of the body hanging freely in the lumen. In some of the congested regions, there were swollen mesh works of

164

Plate No. 5

(A) T. S. of infected intestine of W. attu, parasites in the lumen × 10

(B) T. S of infected intestine of W. attu, showing rupture of

serosa × 10

165

Plate No. 5

Serosa

Mucosa

Serosa

Parasites

Muscularis s

(A)

Rupture of serosa layer

Muscularis

(B)

166

red blood cells, fibroblast with broken blood cells. Basophilic cytoplasm and cell boundaries were poorly defined. The giant cells arranged themselves around the debris.

No significant changes being observed in the early stage of the infestation. During the later stage of the parasitic infestation, border of mucosa were irregular or disrupted, columnar cells were degenerated and goblet cells were enlarged.

The stomach was a sigmoid, highly distensible sac with numerous folds in its lining. The normal stomach wall consisted of five layers such as sub serosa, muscularis, sub mucosa and mucosa. The mucosa is thrown into numerous waves like villi projecting into the lumen. The muscularis mucosa is well developed and lies below the sub mucosa. It consists of an outer longitudinal layer and inner circular layer. The muscularis consists of a thick and prominent layer of circular muscle fibres.

The intestine was a straight, sigmoid or coiled tube. The normal intestine consists of four layers such as serosa, muscularis, sub mucosa and mucosa. The muscularis consists of two layers: an outer thin layer of longitudinal muscle fibers and inner thick layer of circular muscle fibers. The mucosa is folded into numerous simple foods or finger like villi. These villi are numerous in the proximal part and are fused with one another distally.

The histology of liver shows sinusoids which are irregularly distributed between the polygonal hepatocytes are fewer in number and are lined by endothelial cells with very prominent nuclei. Normal liver was large and there was a compound tubular gland consisting of a large number of hepatic acini.

The globular of the pathogenic parasite posses pseudobothrial depressions and an apical sucker which penetrate the epithelium, sub mucosa and muscularis of the intestine in such a way that the head is projecting from the outside of the intestine surrounded by a capsule and causes a serious damage. This was also observed by Bovein (1926). This is however generally found only in case of heavy presence of infection of parasites which effectively blocked the tube of the gut during heavy infection. This is also supported by the findings of Mackiewcz (1972).

167

Plate No. 6

(A) T. S of infected stomach of W. attu × 10

(B) T. S of infected stomach of W. attu showing damages of different layers due to parasite infestation

168

Plate No. 6

Serosa Submucosa

Mucosa

Muscularis

(A)

Serosa

Muscularis

(B)

169

A number of observable histopathological changes occurred in the intestinal tissue of infected fishes. The gut helminthes damaged the walls at the sites of their attachment. This disruption was mainly due to the action of sucker of the parasites. As a result, the intestinal wall was heavily destroyed. Deposited melanin was also observed inside intestinal tissue. The gut wall was perforated where the host tissue reacted vigorously. Large vacuoles were also formed. Fluid filled empty space along with debris and lymphocytes were present. The intestinal mucosa and villi tissue was disrupted, the blood vessels were ruptured and intestinal tissue showed incipient necrosis (Plate – 5 A).

Apparently the intestine was seen with many external swelling other than smooth surface. It was also observed that penetration of this parasites causing proliferation of layers and protuberant curved nodules. The histopathological observation of the infected tissues revealed that this species caused serious pathological changes in the gut as its scolex was deeply buried into the serosa layers. Besides this, the nodular appearance and necrosis with debris in the pit. The nodule formation which seems an inflammatory response of the host, provides sheltered habitat and firmed attachment of the worm (Plate – 9).

In the early stage, there are no significant histopathological changes observed in the serosa, muscularis, mucosa and sub mucosa layer of the stomach. In the later stage, some columnar cells of mucosa layer and mucous cells were degenerated. In some severe cases, the gastric glands were ruptured (Plate – 6) .

In W. attu, trematode (both encysted and free), I. hypselobagri were frequently found in swim bladder and more rarely in body cavity (stomach, oesophagus, mouth, urinary system, billiary system, ovaries, circulatory system). The parasite, I. hypselobagri was found distributed in and around the general viscera. Some cysts of it were also observed in the liver. The main effect of the parasite was done on the skin surface, body musculature and visceral organs. I. hypselobagri (immature) were found attached to the body muscles causing extensive tissue damages including inflammation, necrosis and empty spaces with fragmented blood capillaries, tissue debris, lymphocytes and fluids. Due to the structural construction and the ability of the

170

Plate No. 7

(A) T. S of non-infected liver of W. attu × 10

(B) T. S of infected liver of W. attu having multiple sinusoids × 10

171

Plate No. 7

Normal sinusoids

Liver cell

(A)

Enlarged sinusoids

(B)

172 immature I. hypselobagri, they are normally capable of dissolving and penetrating the skin and muscle layers when they are living in the regular habitat and corresponding micro environment. But along with the onset of decomposition of viscera or any unusual change of host body’s micro environment, the trematode become stimulated or compelled to utilize the dissolving and penetrating capacity for their survival. It can be noted as a homeostatic adjustment or adaptation of the juvenile trematode I. hypselobagri. The juvenile parasites dissolve the skin with the help of the penetration glands, located in the oral sucker situated at the anterior region of the body and in the acetabulum.

Heavy melanin deposition was observed along with accumulated melanin macrophage centers in the infected liver. Due to the presence of I. hypselobagri as well as cyst, small vacuoles were formed in the liver. The melanin-macrophage centers should possibly be considered as a component of the reticulo-endothelial system and hence, part of the defensive system of the fish against any infection. Presence of massive melanization again confirms this. Sometimes hepatic blood vessels were ruptured. The affected liver showed mild hepatic or hemopoietic degenerative changes with hemorrhages (Plate – 8) .

During the migration of immature I. hypselobagri from visceral cavity to the swim bladder, massive disruption and dislocation of the visceral organs occurred. Irregular black pigmentation was scattered throughout the swim bladder, due to the infection by juvenile I. hypselobagri. In severe cases, the alveolar sacs and capillary plexuses were disrupted causing necrosis.

Due to the severe infections of Pallisentis umbellatus, causes damage of muscularis layer forming mass of cluster. These species obviously causes mechanical obstruction and denudation of the epithelial layer within the gut occupying a major portion of the intestinal cavity of the lumen and thus allow in a narrow space for the chime to pass through. Moreover, larval forms also cause the barrier of the chime to pass and ultimately a total blockage of the results. The chime on passing through such a narrow space of the lumen causes gradual disruption of the gut and finally disappearance of the tissue system.

173

Plate No. 8

(A) T. S of infected liver of W. attu showing deep carbon deposition × 10

(B) T. S of infected liver of W. attu showing heavy melanin pigmentation × 10

174

Plate No. 8

Carbon deposition

(A)

Melanin pigmentation

(B)

175

All the parasites were found in the stomach and in the intestine either with their head attached to the gut or exposed eely in it. Most of the acanthocephalans were attached only superficially to the wall of the gut, but Cavisoma magnum did penetrate the epithelium, sub epithelium, sub mucosa and muscularis layer, in such way that the head penetrates out of the gut and were surrounded by a capsule.

It was revealed from the sections of a portion of the intestine that there was a severe damage in the mucous membrane with the broken villi. The parasites were observed to move forward leaving a considerable portion of the intestine only with serosal layer Polyoncobothrium polypteri, the truncated cone-shaped scolex of the species was found to attach firmly to the wall of the intestine, causes lesions and inflammation; generally capable of local damage ( Plate – 5 B).

Lesions occur within the muscularis of the stomach and external serosa is involved in any generalized peritonitis due to tapeworms. The stomach wall of the host was infected by nematode parasites. Histopathological examination confirmed that the stomach wall was severely damage due to the penetration of these larvae into the muscular layers. The serosa was destroyed and many sections of larvae were observed among the muscularis mucosa and the connective tissue. Below the encapsulated parasite, the muscularis layer was found to be damaged (Plate – 6 B).

The Quimperiidae larva was found in several organs namely mesenteric layer, stomach and intestine wall, liver, kidney, gonads and outer peritoneal layer etc. this larval nematodes forms cysts into the above mentioned organs of the general viscera including fat bodies. Each larva was enclosed with in a capsule which was a flattened spore composed primarily on the fibrous tissue of the hosts. The encystment caused retardation of the proper growth of gonads and the fibroblast tissues on the stomach and intestinal wall of the hosts.

Cosmoxynemoides aguirrei and Contracaecum L3 larva found attached in the epithelial layer of the stomach with their chitinous buccal capsules and causes local damage. The encystment of larval nematodes on the outer wall of digestive tract of W. attu caused local damages and mechanical destructions which also supported by Hine and

176

Plate No. 9

(A) T. S of infected intestine of R. rita with free parasites × 10

(B) T. S of infected intestine of R. rita, mildly effected × 10

177

Plate No. 9

Serosa

Mucosa

Submucosa

Parasites

Muscularis

Damaged portions

(A)

Serosa

Mucosa

Parasites

Muscularis

(B)

178

Kennedy (1974). Destruction and distention of muscularis affected due to the encystations of the nematodes associated with their presence, was a proliferation of the epithelial cells. Blood cells infiltration was being observed.

Black pigment was also found around the capsule. In severe cases of pathogenecity, muscular layer was found to become hyperplastic and at times a thin mucolid interface layer was also observed.

In some, liver infection was also extremely deep with degeneration, resisting in nodular regeneration hyperplasia, which was causing compression of hepatic parenchyma, which was severely fatty. This nodular hyperplasia caused fatty changes and mild chronic congestion of irregular distribution (Plate – 11 B).

The most salient feature of the sections of the liver was damaged to the hepatic parenchyma. All gradation from degeneration to extensive necrosis of hepatic cells may be encountered depending on the duration and severity of the infection. The pathology associated with parasites was thought to be caused by proteolytic secretions of the frontal glands. However, the occurrence of necrotic debris in the present study is suggestive of the presence of proteolytic enzymes in the parasites. Histopathologically compared to that of the healthy liver cell, in the early stage of the parasite’s presence there were no signifant changes in the parasitic liver.

The section of cyst consisted of epitheloid tissue and ultimately fibrous tissue. The hepatic cells of the infected area underwent atropy and necrosis. The lobules collapsed, circulatory disorder occurred and the degree of cell damage were mild to severe were being observed. Hemorrhagic areas were frequently seen in infected areas.

In the late stage of the infestation, the liver tissue showed the inflammation of the surface layers. Some polyhedral hepatic cells near periphery were mostly necrotized. Focal lyses were often observed in the hepatopancreas, inside the hepatic parenchyma and adjacent to the blood vessel. Blood vessel was observed as degenerated. Little dark pigmentation was also found. Histopathological sections of the infected liver

179

Plate No. 10

(A) T. S of infected stomach of R. rita × 10

(B) T. S of infected stomach of R. rita showing juvenile parasites burrows deep in the muscularis × 10

180

Plate No. 10

Mucosa

Submucosa

Fibrous tissue

(A)

Rupture of serosa layers

Parasites (juvenile)

(B)

181

Plate No. 11

(A) T. S of infected liver of R. rita having eroded tissue × 10

(B) T. S of infected liver of R. rita with damaged liver cells, caused hemorrhage and breakage of blood cells, coagulation necrosis of parenchyma × 10

182

Plate No. 11

Enlarged sinusoids

Eroded tissue of liver

(A)

Blood hemorrhage

Liver cells

Vacuoles

(B)

183

tissue showed that encapsulated cystic form of nematodes were present in the liver. Sometimes the liver was destroyed by cestodes because of heavy infections. The tissue mainly caused inflammation by the cyst of cestode larvae and caused injury to the tissue, damaged liver cells, caused hemorrhage and breakage of blood cells, coagulation necrosis of parenchyma, large areas of parenchyma was replaced by the cyst of the parasite.

184

CHAPTER – 6

PROXIMATE ANALYSIS OF THE FISHES AND VARIATION DUE TO INFESTATION

Biochemical analysis of different nutritional components of Wallago attu and Rita rita

In the present study, an attempt has been taken due to determine the percentage (g/100 g) of nutrients such as moisture, ash, fat, protein, carbohydrate contents (mg/100 g) and energy (K cal) in W. attu and R. rita.

The results of the proximate composition of W. attu and R. rita have been analyzed to compare the values of components in the two species of infected and non-infected fishes, in different size groups and also due to determine the relationship of the nutritional components with rate of infestation.

In infected W. attu, the moisture was 74.48 g/100g, ash 1.01g/100g, fat 2.34g/100g, protein 15.28g/100g and carbohydrate was 6.89%. While in non-infected W. attu, the different nutritional elements were: moisture 75.66g/100g, ash 1.4g/100g, fat 2.47g/100g, protein 15.76g/100g and carbohydrate was 7.34% (fig-a).

80 74.48 %

20 15.28 %

10 6.89 % 1.01 % 2.34 % 0 Moisture Ash Fat Protein Carbohydrate

In Infected Fish

185

80 75.66 %

20 15.76 %

10 7.34 % 1.4 % 2.47 % 0 Moisture Ash Fat Protein Carbohydrate

In Non-infected Fish

Fig a. Presence of nutritional components in infected and non-infected W. attu

In infected R. rita, the percentage of nutritional components were as, moisture: 73.61g/100g, ash 1.12g/100g, fat 5.51 g/100g, protein 16.45g/100g and carbohydrate was 3.27 %. Besides these, the non-infected R. rita contains the nutritional components as- the moisture 74.09g/100g, ash 1.43g/100g, fat 6.07g/100g, protein 17.11g/100g and carbohydrate was 3.95% (fig-b).

80 73.61 % 70

20 16.45 %

10 5.51 % 1.12 % 3.27 % 0 Moisture Ash Fat Protein Carbohydrate

In Infected Fish

186

80 74.09 % 70 60 50 40 30 20 17.11 % 10 6.07 % 1.43 % 3.95 % 0 Moisture Ash Fat Protein Carbohydrate

In Non-infected Fish

Fig b. Presence of nutritional components in infected and non-infected R. rita

In 2011, the percentage of moisture content in W. attu was higher in winter (74.99 g/100g, Feb’11) whereas the lower moisture content was recorded in rainy season ( 73.92 g/100g, Oct’11). In 2012, the maximum percentage of moisture was recorded in winter (74.96 g/100g, Dec’12) while the minimum was in summer (73.32 g/100g, May’12) [Fig-86].

75.5

74.5

73.5 Moisture(%) 73

72.5

72 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 86. Monthly presence of moisture in W. attu

187

The pattern of seasonal variation of percentage of protein content in W. attu was recorded maximum in winter (15.41 g/100g, Nov’11) and the value was lowest during summer (15.07 g/100g , in April’11). In 2012, the highest percentage of Protein content 15.44 g/100g was observed during summer (April’12) while the lowest was 15.13 g/100g recorded in winter (Nov’12) [Fig-87].

15.5

15.4

15.3

15.2

15.1 Protein (%) Protein 15

14.9

14.8 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 87. Monthly presence of protein in W. attu

In 2011, the percentage of carbohydrate in W. attu was higher during winter (6.9 g/100g, Dec’11) and lower during summer (6.66 g/100g, Mar’11) while in 2012, the maximum percentage was recorded also in winter (6.97 g/100g, Nov’12) and the minimum was in rainy season (6.85 g/100g,Oct’12) [Fig-88].

In 2011, the highest value of fat in W. attu was observed during winter (2.47g/100g, Nov’11) and the lowest value was in winter (2.11g/100g, Feb’11). The next year, the value was higher in rainy season (2.51 g/100g, Sep’12) while the lower was found in rainy season (2.21 g/100g, July’12) [Fig-88].

188

7 N u 6 t 5 r i 4 Carbohydrate e 3 Fat n t 2 s 1 0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 88. Monthly presence of nutritional components (fat and carbohydrate) in W. attu

1.1

1.05

0.95 Ash Ash (%)

0.9

0.85

0.8 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 89. Monthly presence of ash in W. attu

In 2011, the maximum percentage of ash in W. attu was recorded during rainy season (1.06g/100g, Oct’11) while the minimum was in winter (0.97g/100g, Dec’11). On the

189 other hand, in 2012, the highest value was found in summer ( 1.06g/100g, Mar’12) and the lowest value was found in rainy season (0.98g/100g, July’12) [Fig-89].

In R. rita, in 2011, the percentage of moisture was higher in rainy season (73.92 g/100g, Oct’11) whereas, the lower moisture content was recorded in winter ( 73.22 g/100g, Dec’11). In 2012, the maximum percentage of moisture was recorded in summer (74.39 g/100g in April’12) while the minimum was also in summer (73.04 g/100g in June’12) [Fig-90].

74.5

73.5

Moisture (%) Moisture 73

72.5

72 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 90. Monthly presence of moisture in R. rita

The pattern of seasonal variation of percentage of protein content in R. rita was recorded maximum in 2011 in summer (16.69 g/100g, May’11) and the value was lowest during rainy season (16.26 g/100g in July’11). In 2012, the highest percentage of protein content 16.66 g/100g was observed during rainy season (Sep’12) while the lowest was 16.35 g/100g recorded in rainy season (July’12) [Fig-91].

190

16.8 16.7

16.6 16.5 16.4 16.3 Protein (%) Protein 16.2 16.1 16 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 91. Monthly presence of protein in R. rita

6 N u 5 t r 4 i Carbohydrate e 3 n Fat t 2 s 1

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 92. Monthly presence of nutritional components (fat and carbohydrate) in R. rita

In 2011, the percentage of carbohydrate in R. rita was higher during winter (3.41 g/100g, Dec’11) and lower during rainy season (3.14 g/100g, Aug’11) while in 2012, the maximum percentage was recorded also in summer (3.36 g/100g, May’12) and the minimum was in rainy season (3.21g/100g, Aug’12) [Fig-92].

191

1.4

1.2

0.8

0.6 Ash Ash (%)

0.4

0.2

0 J F M A M J J A S O N D J F M A M J J A S O N D January 2011 - December 2012

Fig 93. Monthly presence of ash in R. rita

In 2011, the highest value of fat in R. rita was observed during summer (5.69g/100g, May’11) and the lowest value was in winter (5.33g/100g, Dec’11). In 2012, the value was higher in winter (5.77 g/100g, Nov’12) while, the lower was found in summer (5.26 g/100g, April’12) [Fig-92].

In Jan-Dec’11, the maximum percentage of ash in R. rita was recorded during winter (1.13g/100g, Dec’11) while the minimum was in rainy season (1.01g/100g, Aug’11). In 2012, the highest value was found in winter (1.29g/100g, Feb’12) and the lowest value was found also in winter (1.09g/100g, Jan’12) [Fig-93].

192

CHAPTER – 7

GENERAL DISCUSSION

Knowledge of identities of the metazoan parasites of Wallago attu and Rita rita will assist fish culturists when determining the specific treatment needed to overcome disease outbreaks. The present research and investigated results provide information on the parasite fauna of the catfish in Bangladesh, give preliminary information on the prevalence and intensities of infection of individual taxa, their pathological effects on nutritional components and the impact of host age on the prevalence and abundance of the parasites. The parasites may effects its host in various ways that may include the utilization of host’s food, destruction of hosts tissue, abnormal growth, mechanical inferences, biological effects, various kinds of tissue reactions as well as the effects of toxins, poisons or secretion of parasites itself.

Diseases affect the normal health conditions and cause reduction in growth, abnormal metabolic activities and even resulting in great economic loss. Health of any population depends on the control of disease and maintenance of a healthy relationship between living creatures and their environment (Snieszko, 1983). Diseases are the most serious limiting factors in aquaculture because of increased density of fish in restricted water where the fish pathogens can easily transmit from one fish to another. Much economic loss is however preventable with proper fish health management (Kabata, 1985).

The parasite may cause fish morbidity and mortality in culture fishes where the entire fish population of pond may be killed, resulting in loss of potential food and economic loss to the culturists. The success of the implementation of various fishery development programs depends to a certain extent on the intensification of the fish parasitological research, as the improvement of fish yield can mainly be achieved from healthy fish stock (Srivastava, 1977).

Bashirullah (1973) mentioned that smaller fishes contained less parasites while the larger fishes contained greater numbers. In the present study, a total 11 species of

193 parasites were recovered from W. attu whereas, 9 species from R. rita. The result showed that most parasites have some special preference in their site selection to some degree. The changes occurred as the parasites become overcrowded in their niche (Mackiewicz, 1972). In the present investigation, it was observed that intestine was favored by many parasites. According to Bullock (1963) and Dogiel (1964), the intestine of fish is usually more infected than any other organ. It may be related to the fact that due to easy availability of nutrients in the intestine, parasites favor this niche.

It is difficult to explain the reasons of seasonal variation in the infection of helminth parasites in fishes without knowing the seasonal aspects of the intermediate host- parasite system. Although changes of parasite incidence are attributed to diet and other factors such as host size and development of host immunity; it is not unlikely that immunity plays an important part in determining incidence (Scott, 1975 a).

In W. attu, it was evident that during winter months (remarkably in December and February) maximum number of parasites were found. In R. rita, seasonal abundances of total parasite showed distinct peak period of abundance (100%) during wet season (rainy months). This may be due to: a) heavy rainfall, b) flood, c) various kinds of pollutants such as, industrial pollutants, pesticides, insecticides, domestic sewage etc. d) decreased immunity of hosts. This coincides with the findings of Zaman (1985), Khanum and Begum (1992); where they agreed that, the seasonal abundance of the helminth parasites are significantly correlated with the seasonal rainfall.

A wide range of factors, both density-dependent and density-independent could affect various aspects of the seasonal variation of helminth infestation in an aquatic ecosystem (Chubb 1977, 1979, 1980, 1982). Furtado and Tan (1973) indicated increase in infection occurred with the increase in size of fish of C. batrachus and according to them; it was due to a change in diet of the fish. Similarly, Pennicuick (1971) observed the large increases in the incidence and intensity of Schistocephalus infections in small young fish was due to the accumulation of parasites when the young fish ate more infected intermediate hosts than the larger fish. It indicates that

194 the growth of fish promote the tendency of parasites infestation and parasite burden. In case of male, the fish’s growth promotes the prevalence and intensity also. This indicates that parasites were not strictly regulated by the host. There is a fluctuation in intensity and prevalence. But usually intensity is inversely correlated with prevalence and follows established patterns of distribution i.e a contagious distribution (Eliott, 1979).

The majority of the studies on seasonal patterns of infestation of helminthes of freshwater fishes have been in the temperate climate zone of the world, with very little information available on the tropical rainy climatic zones. There has been considerable speculation on the observed temperate zone seasonal patterns, with the most significant factors being thought to be water temperature variation (Aho et al. 1982; Camp et al. 1982; Esch, 1983; Granath and Esch, 1983 a; Kennedy, 1977), host behavior (both dietary and social, Anderson, 1976; Kennedy, 1977; Smith, 1973) and parasite population density (Esch, 1983; Granath and Esch 1983 b; Holmes et al. 1977).

The parasite which was dominant in a particular fish host, may or may not maintain its dominance in another host. Amin (1975) supports the view that the presence of a parasite species in significant number in a fish host, results a lower density of the other species of parasites. Dogiel (1961) discussed the dependence of the parasite fauna on the environment. He stated that the parasite fauna of all fishes depends on the geographical location, season, the characteristic of the water (temperature and chemical composition), type of the bottom and other biotic and abiotic factors. He also stated that the parasitic fauna is affected even more seriously by the physiological and biological features of the host. Food of host includes many animals which serve as the intermediate hosts for the parasites completing their life cycles in fishes. The ability of the host to develop immunity, the age of the host, health condition, spawning and migration of the fish are also very important factors to determine the final composition of parasite fauna of the fish.

Bashirullah (1972 a) investigated the distribution and occurrence of Isoparorchis hypselobagri in different hosts and localities from Bangladesh water. Out of 25 hosts,

195 he recorded seven new hosts from Dhaka, Bangladesh. He collected Isoparorchis hypselobagri from swim bladder of Wallago attu, Mystus aor, M. cavassius and from lateral muscles of Channa striatus, C. marulius, C. punctatus and Nandus nandus. He found juvenile of Isoparorchis in the lateral muscles of fishes within heavily pigmented cysts. He believed that the parasite actively penetrate the gut wall and migrate into the swim bladder of siluroid fish. He also discussed the life history of the trematode parasite. In 1988, Zaman and Leong worked on two fresh water cat fishes. They described the intensity and abundance of infestation of I. hypselobagri from the two cat fishes Clarias batrachus and C. macrocephalus. Similar result was also observed by Chowdhury et al. (1986) in genus Mystus. But the degree of intensity and abundance were different.

The food habits and diets of the two hosts followed the same pattern so the pattern of occurrences of parasites was almost similar and more than one host served as the definitive host. Chauhan and Ramakhrishna (1958) worked on the distribution and abundance of cestodes of eleven species of teleosts (Barilius sp., Labeo sp., Mastacembelus sp., Ophiocephalus sp., Schizothorax sp. and Tor sp.) from Garhwal Himalayas with a note on host biology. They observed no consistent pattern in differences in quantity of food eaten by the two sexes and expected that both sexes would stand an equal chance of being infected by the cestode parasites which require an intermediate host. Difference in infestation between the sexes could be either of the two points of Wickins and MacFarlance (1973):  It is merely a reflection of differential feeding either by quantity or quality of species or  Due to the different degrees of resistance to infestation by different sexes. The different categories of food taken by W. attu and R. rita were almost similar but the type and rate of establishment of infection were different due to susceptibility of the host, different biochemical composition and different ecological and physiological mechanism in the two host spp. Besides, the diets of the two fish spp. were directly or indirectly related with the parasite fauna. Small fishes, insects and mollusks were found to have been consumed as major portion of the diet in both the fishes. Insects and mollusks serve as the intermediate host for many larval helminths. Ascaroid larvae

196 were transmitted through the small fish consumed. This view also supported by Bashirullah (1973), Wooten and Smith (1975), Khanum et al. (1990). Aquatic insects served as the intermediate hosts for cucullanidae, quimperiidae and other families of nematode. Insects also served as the intermediate hosts for acanthocephalan parasites where the arthropod must eat an egg voided with the feaces of a definitive host. Mollusks serve as the intermediate host for many larval trematodes. The siluroid and non-siluroid fishes, which feed on plankton copepod are highly susceptible to infection of I. hypselobagri metacercaria in the swim bladder and on feeding these infected fishes the carnivorous siluroid fishes become infected and thereafter, the metacercaria develop into juvenile or immature form, occupy the habitats like coelomic cavity, kidney, musculature and visceral organs of those fishes (Srivastava, 1977 and Cribb, 1988). In the similar way, the infective larvae of camallanid nematodes released into the water directly by ovoviviparous females are taken by copepods which in turn are eaten by small forage fishes and through this channels the nematodes could be passed to large predatory species when they consumed these forage fishes (Stromberg, 1973).

As it can be ascertained that, the sources of infection in both the fishes were same due to same type of food habits, different biochemical composition and manifestations of effects of interaction of some complex and often obscure ecological and physiological mechanisms in W. attu and R. rita, the type and rate of establishment of infection were different. According to Zaman (1985), Lytocystus lativitellarium was dominant in Clarias macrocephalus but not in C. batrachus though they shared the same habitat and consumed same type of food.

In the present study, Isoparorchis hypselobagri, Macrolecithus gotoi, Echinorhynchus kushiroense, Pallisentis ophiocephali, Acanthocephalus aculeatus, Contracaecum L3 larva in W. attu were restricted to specific site or organ, but other individual species of parasites were not found in specific site within the same host fish. Whereas, juvenile Isoparorchis hypselobagri in W. attu was found to very specific in site preference. Some species of parasites occupied narrower microhabitat than others, whereas others may be more flexible and occupied greater areas (Awachii, 1968; Mackenzie and Gibson, 1970; Ulmer, 1971; Holmes, 1973; Hine, 1980; Evans, 1977) concluded that the

197 different site preferences of the parasites may be explained by inherent differences among the parasite species which dictate their responses to stimuli thus bringing them to be localized establishment and any subsequent migrations, influenced by certain biochemical and physicochemical gradients in the different organs of the host.

In the present study, it was evident that, prevalence and intensity of trematodes and nematodes varied greatly in both the years of the study period in both the host fishes. Few different species of parasite were also found in this investigation affecting the two host separately. It was also observed that maximum length was recorded 66 cm. for W. attu, whereas it was 41 cm for R. rita.

In the present investigation, it was observed that a large proportion of immature nematodes, acanthocephalans, trematodes and cestodes were also found to infest host fishes. According to Holmes et al. 1977, the maturation of the parasites in the catfish might be controlled by density-dependent factor and population number. They clarified their statement by saying that the greater the number of parasites in a host, fewer of them will mature. This phenomenon also was supported by Zaman, 1985.

Host age (=length) is an important factor in determining the parasite fauna of fish (Zaman, 1985). The exact mechanisms, include the factors, namely, (1) composition and quality of diet, (2) differences in habitat preference between juveniles and adults, (3) development of age acquired immunity to specific species of parasites of and (4) the accumulation of long-lived parasites species (Arthur et al. 1982) and etc. The long-lived larval helminthes, such as Isoparorchis hypselobagri and of some nematodes occurring in the mesenteries and viscera are undoubtedly found accumulated with age as observed in the present study, but this could not be clearly demonstrated in the present analysis and an intensive, systematic investigation should be carried out for several years to obtain a clear picture of the role of host age in determining the parasite fauna of Wallago attu and Rita rita.

Furtado and Tan (1973) showed that Lytocestus parvulus and L. lativitellarium increased with the increase of the length of Clarias batrachus from Malaysia. Ahmed

198 and Sanaullah (1978) showed that infection of Djombangia penetrans and L. indicus increased to maximum in the 19 cm. length groups of Clarias batrachus in Bangladesh and then decreased. In the present study of parasite in catfish in Bangladesh, the results of the effect of age on parasite abundance varied.

Scott (1975 a and b) worked on incidence of trematode parasites of American Plaice Hippoglossoides platessoides in relation to fish length and food. He stated that the incidence of several trematode species changed with the length of fish and associated changes in the fish’s diet. Correlations between parasite incidence and frequency of occurrence of food items indicated that small crustaceans may be intermediate hosts for Steringotrema vetustum and Derogenes.

Histopathological studies showed that skin, muscle layer, stomach, intestine, swim bladder, liver were damaged by the infection of helminthes parasites. Helminths in fishes are also recognized as causing serious effect on their hosts (Ribelin and Migaki, 1975). Multiple changes occurred in the liver for parasite infestation. One of them is vacuole formation, causes spongy appearance where fluid accumulated thus the surrounding cells faces more pressure and the normal liver function hampered and also the hosts immunity decreased. These reasons promote the possibility of primary and secondary infection.

Mackiewicz et al. (1972) found cellular damage, mechanical obstruction, production of lesions and necrosis etc. caused by the helminthes in different organs in fish. Some remarkable works have been done on histopathology of catfishes by Bhattacharjees, 1986; Khanum, 1994; Khanum and Farhana, 2002; Soderberg, 1984 etc. Due to the infestation of I. hypselobagri in the swim bladder, massive melanization was observed. In the body musculature, intestine and kidney fluid filled empty spaces along with debris’s and lymphocytes were present. Similar observation also reported by Roberts et al. (1993) and Sanaullah et al. (1997).

In the present study, no notable pathological damage was observed due to the encysted larvae in mesenteric and viscera. Kenndy and Lie (1974) observed that

199 capsulated larval Eustrongylids sp. found attached to the stomach wall of Salmo trutta, had no local pathological effect. But Ahmed and Rahman (1979) reported pathogenecity of three encysted nematodes on the stomach wall of flat fishes where local damage and mechanical destruction were observed. The caryophyllaeid cestodes inflicts by their scolex, as they anchor to the wall of the stomach and intestine and causes shallow ulcers and lesions. Due to severe infection of these species, intestine becomes porous through the epithelial layer and ultimately become sieve-like.

In the present work, it was observed that the worms burrowing deep into the muscularis, nodule was formed. Inflammation and compression of tissue layers were noticed at the site of attachment of cysts to the intestinal wall of the host. In some cases, a thin mucoid interface layer was seen between the host tissue and the cyst of the worm. Loose muscle fibers were also evident. Necrotic tissue surrounded the cyst of the worm and blood cells infiltration was observed. So, the present observation indicates several host tissue reaction resulting into degeneration and encapsulation of larvae, ultimately resulting into the formation of fibrous nodules. This also causes destruction of muscular layers of the intestine wall of the fish.

The tissue damage by the caryophyllid cestodes was severe and extensive in C. selangor, Malaysia. It was reported from the same species of catfish from Bangladesh (Ahmad and Sanaullah, 1976 and 1977). Thomas (1964) suggested that, the parasites, which cause extensive tissue damage, may provoke a strong host reaction thus rendering that area of the host fish unsuitable for attachment by other parasites.

Fish constitute an important source of essential macro and micro- nutrients in which Bangladeshi have been shown to be chronically deficient (Ahmed and Hassan, 1982). The moisture performs a vital role as a solvent, mineral nutrients and other foodstuff being transmitted in solution throughout the animal body and also essential for most of the physiological reactions in animal tissue and in its absence life do not exist (Singhvi et al. 1987). Ash mainly rich in minerals specially calcium, potassium, sodium, chlorine and phosphorus. Dietary fat helps in the absorption of fat-soluble vitamins, also play a good part in the regulation of the body temperature.

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Protein contains nitrogen, carbon, hydrogen and oxygen. Protein got multiple physiological importance as a growth material for the organism, a part of fuel of the organism, structures of living materials are composed of different types of protein molecules. Carbohydrate is readily available fuel of the body, constitutes the structural material of the organism plays as a key role in the metabolism of amino acids and fatty acids. The above mentioned nutritional components promote the value of Wallago attu and Rita rita to the common people and make them more interest to take these fishes enormously than the other fishes.

A fluctuation in the individual biochemical components of the flesh, throughout the yerar was observed in both infected and non-infected fishes. Protein, carbohydrate, fat contents were higher in winter (dry months) than the summer (hot months), analysis which agrees with Adhikari and Noor (1967) in case of Puntius puntius. On the other hand, it is also evident from the present results that moisture was higher in winter and lower in summer. Moisture content was always higher in infected female than infected male in both the fishes because during spawning period the fishes naturally showed lower percentage of nutrient contents. Rubbi et al. (1987) showed that in case of some fresh water fish, moisture contents were higher, protein and fat contents were lower in matured female fish with eggs.

In this present investigation, some parasites were recovered which are basically parasites of marine fishes and piscivorous birds. This may be due to, parasites are becoming more diverged and fresh water is being contaminated with marine water in the estuaries, on the other hand these birds may transfer the parasites while taking the fishes as their food. Although considerable efforts have been given on parasites taxonomy, it is still impossible to obtain an accurate picture of the parasite fauna of Bangladeshi fishes. Because, Bangladesh is a deltic country and is subject to extensive flooding, it is possible for marine and estuarine fishes to move for upstream, bringing with the much of their marine parasite faunas. Feeding by fresh water carnivorous fishes on marine or anadromous fishes may result in the temporary

201 transfer of gastro intestinal parasites. In a number of cases, this appears to have resulted in typically marine helminth fauna being reported from freshwater hosts.

In conclusion, controlling measures should be taken to interrupt the steps of parasitic transmission from one host to another. Emphasis should be given to control the parasites with a view to increase the protein production together with the rapid growth of fishes. These two fishes are over burdened by huge number of helminth species because the rivers and other water bodies’ of the country are not protected. Very frequently these are polluted by flood, climatic disaster, industrial wastes, pesticides etc. Due to these environmental degradation and continuous contamination, parasitic adaptation to the hosts are increasing day by day and gaining more diversity.

Therefore, extensive study should be carried out on the trematode and nematode parasites of Wallago attu and Rita rita, otherwise the pathogenecity caused by them, by damaging the tissues and decreasing the nutritional values, will lower the productivity of these fishes.

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CHAPTER – 8

SUMMARY

The present study was conducted on Wallago attu and Rita rita, collected from Swarighat, Dhaka during January 2011 to December 2012, to observe different aspects: their parasite infestation, impact of parasitism on length, sex, food and feeding habits, climatic factors, pathological effects of parasite infestation and difference in nutritional contents of the infected and non-infected fishes.

To study the length frequency distribution and to determine the relationship of parasite infestation with length of the fish, the total length of W. attu (35 – 42 cm, 43 – 50 cm, 51 – 58 cm and 59 – 66 cm) and R. rita (22 – 26 cm, 27 – 31 cm, 32 – 36 cm and 37 – 41 cm) were divided into four length groups with regular intervals.

Regarding the food and feeding habits, the “Occurrence method” (Hynes, 1950) was followed. The food items were grouped into five categories: small fishes, crustaceans, insects, mollusks and others (macrophytes, sands, mud etc.). For collection of ecto and endoparasites, the gill chamber with gills, skin, fins, alimentary tract (from mouth to anus), body cavity, swim bladder, liver etc. were examined. The collected parasites were fixed, stained and preserved (according to Cable, 1963). For histopathological study, the fish tissues were separated and treated according to the methods given by Drury and Wallington (1967).

In the present investigation, the analytical determination of nutrient contents (moisture, protein, fat, carbohydrate and ash) of W. attu and R. rita were done by the conventional methods demonstrated by A.O.A.C., 1975 and Pearson, 1962 on weight basis. The techniques for analysis of data and the terms used to denote the relationships of host-parasites were expressed according to Margolis et al. (1982). To complete the statistical calculation of the present data, the “chi-square test”, proportion test (p =), correlation-coefficient test (r =) and simple significance of student “t-test” (Baily, 1959; Winifred, 1972) were computed.

Out of 250 specimens of W. attu, one species of ecto-parasite (Argulus foliaceus) and 10 species of endo-parasites were recovered of which three trematodes

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(Isoparorchis hypselobagri, Macrolecithus gotoi, Magnacetabulum trachuri); two nematodes (Contracaecum L3 larva, Cosmoxynemoids aguirrei); one cestode (Polyoncobothrium polypteri) and four acanthocephala (Echinorhynchus kushiroense, Pallisentis ophiocephali, Acanthocephalus aculeatus, Pallisentis umbellatus).

In W. attu, the endoparasites had an overall prevalence of 34.4% with a mean intensity of 1.66 ± 0.24 per infected fish. Statistical analysis by “Proportion test” showed the overall proportion of infected W. attu differs significantly at 5% level of significance between two periods 2011 and 2012 (P < 0.05). The seasonal study of helminth infestation revealed that the minimum prevalence were found in the month of February’11, May’11, August’11, September’12 and November’12. The maximum value showed during the month of December’11 and February’12. The ecto-parasite showed 23.6% as prevalence and 3.11 ± 1.47 as mean intensity per infected fish.

A total of 350 specimens of R. rita were examined; one species of ecto-parasite (Lernaea cyprinacea) and eight species of endo-parasites (Notoporus leiognathi, Saccacoelium obesum, Sterrhurus musculus, Clinostomum piscidium, Ascaroid larva, Cavisoma magnum, Corynosoma alaskense and Corynosoma strumosum) were found. An overall prevalence of 64.57% and mean intensity per infected fish, as 2.64 ± 1.12 were recorded for endo-parasites.

In R. rita, the average prevalence of helminth infestation was comparatively higher in 2011 (86.32%) than in 2012 (35.33%) and the prevalence differs with strong significant (P < 0.05) even at 1% level of significance. While in case of mean intensity of total parasites, the intensity was found to be strongly significantly associated (P < 0.05) in both the years.

The seasonal study of helminth infestation in R. rita revealed that minimum prevalence recorded in January’11 and May’12 while maximum was recorded in July of both the years. Highest mean intensity (2.75 ± 0.68) was recorded in May and lowest (2.12 ± 0.53) in September, 2011 while in 2012, the maximum rate (8.00 ± 2) was in May and minimum in November (2.33 ± 0.58).

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In W. attu, the mean number of parasite species per infected fish was 1.84 ± 0.46 in 2011 and 1.4 ± 0.35 in 2012. In R. rita, the mean number of species was 2.33 ± 0.58 in 2011 and 4.08 ± 1.02 in 2012. In both the species of host fishes, the minimum number of parasite species were found in the months of August and November of both the years.

During the study period, the trematodes were the most dominant group of parasites, comprising 59.12% of the total number of parasites collected from R. rita. A total of four species of trematode parasites were observed in R. rita while in W. attu, they were three. On the other hand, the acanthocephalans were the most dominant group in W. attu, comprising 47.9% of the total number of parasites. A total of four species of acanthocephalan parasites were observed in W. attu while there were three species in R. rita.

The intestinal trematode, Macrolecithus gotoi was the most numerically dominant trematode, found in the intestine of W. attu and the prevalence was 3.2% with 1.87 ± 0.46 as mean intensity. The occurrence of this trematode was recorded 10.41% of the total number of parasites collected and 31% of the trematode fauna observed. The maximum prevalence (18.18%) of Macrolecithus gotoi was found during January’12 and minimum prevalence (8.33%) was observed in December’12. The prevalence of M. gotoi was recorded highest (8.2%) in 43 – 50 cm length group and lowest (2.6%) in the largest length group (59 – 66 cm). The highest intensity (1.3 ± 0.32) of M. gotoi recorded in the smallest length group (35 - 42 cm).

The next dominant trematode of W. attu was Isoparorchis hypselobagri, the prevalence and mean intensity of this parasite were 5.2% and 1.54 ± 0.38. The occurrence of I. hypselobagri accounting for 13.88% of the total parasites and 42% of the trematode group in W. attu. The maximum prevalence (18.18%) of I. hypselobagri was found in March’11 and minimum prevalence (9.09%) was observed in December’11. It was confined only in swim bladder. The prevalence of I. hypselobagri showed the highest (15.8%) in the smallest length group (35 - 42 cm) and the lowest (2.6%) observed in the largest length group (59 – 66 cm). With gradual increase of incidence of I. hypselobagri

205 from smallest size group to the intermediate size groups, the prevalence suddenly decreased to minimum in largest length group.

The intestinal trematode, Saccacoelium obesum was the most numerically dominant trematode, found in the intestine of R. rita and the prevalence was 12.3% with 2.42 ± 0.61 as mean intensity. This parasite composed 17.42% of the total parasite and 29% of the total number of trematodes. The prevalence of S. obesum was recorded highest (25.8%) in 32 – 36 cm length group and lowest (12.6%) in 27 – 31 cm length group. The intensity of S. obesum was recorded highest (1.9 ± 0.47) in the largest length group (37 – 41 cm) and lowest (1 ± 0) in 27 – 31 cm length group.

Among the other trematodes found in W. attu and R. rita were Magnacetabulum trachuri, Notoporus leiognathi, Sterrhurus musculus and Clinostomum piscidium showed low prevalence and intensity. These trematodes did not follow any definite seasonal pattern of infestation during the study period.

The gills and branchial cavity of W. attu and R. rita were examined. In W. attu, Argulus foliaceus attached to the host on the skin epithelium of the body and fins and gills. In R. rita, Lernaea cyprinacea found in gill, gill raecker and skin. The intensity of Argulus foliaceus at per infected W. attu was 3.11 ± 1.47 and in R. rita the intensity of Lernaea cyprinacea was 3.34 ± 1.62.

Among the nematodes, Contracaecum L3 larva was found to be the most numerically dominant in W. attu and also dominated the nematode fauna observed in the present study. The prevalence and mean intensity were found 4% and 1.3 ± 0.33. This parasite comprised 9.02% of the total parasite collected and 59% of the nematode obtained from W. attu. The highest prevalence (7.9%) and intensity

(1.3 ± 0.32) of Contracaecum L3 larva recorded in the smallest length group (35 – 42 cm) and lowest prevalence (1.4%) found in 43 – 50 cm length group. The prevalence of Contracaecum L3 larva decreased with the increase of length of fish and this parasite was found to infest the body cavity of W. attu.

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Ascaroid larva was the only nematode found in R. rita, with 4.6% prevalence and 3.31± 0.83 as mean intensity was moderately abundant comprising 8.87% of the total parasites. The prevalence of Ascaroid larva showed the highest (10.1%) in 32 – 36 cm length group and the lowest (7.6%) observed in 27 – 31 cm length group. The highest intensity (1.8 ± 0.45) of Ascaroid larva recorded in 27 – 31 cm length group and lowest (1.3 ± 0.3) found in the smallest length group (22 – 26 cm). In R. rita, Ascaroid larva followed the pattern of increasing incidence with the length of of fish.

Among the acanthocephalan parasites, Pallisentis ophiocephali (W. attu) and Corynosoma alaskense (R. rita) showed higher infestation rate. In W. attu, the prevalence and mean intensity of Pallisentis ophiocephali were 6% and 1.4 ± 0.35. Pallisentis ophiocephali showed the maximum prevalence in winter (18.18%, Dec’11) and in summer (22.22%, Feb’12) while the minimum prevalence of infestation found in rainy season (9.09%, June’11 and Sep’11) and in winter (8.33%, Dec’12). P. ophiocephali showed highest intensity (4 ± 0 in June’11 and 4.5 ± 1.13 in Feb’12) during rainy season and summer respectively and the lowest intensity were (1 ± 0.25 in Sep’11) rainy season and winter (Dec’12).

In R. rita, the prevalence and mean intensity of Corynosoma alaskense were 5.4% and 4.63 ± 1.16. The prevalence of Corynosoma alaskense showed the highest prevalence during rainy season (23.52%, in June’11 and 21.42% in July’12). The lowest prevalence (5.88%) was observed in Sep’11 (rainy season) and Nov’11 (winter). The highest intensity of C. alaskense was found in rainy season (6.25 ± 1.56, in June’11) and in summer (7 ± 1.75, in May’12) while the lowest intensity (1 ± 0.25) was observed during summer (May’11 and Mar’12).

Among cestode, Polyoncobothrium polypteri was only found in stomach and intestine of W. attu which was 3.47% of the total parasites. The prevalence and mean intensity were 2% and 1 ± 0. The highest prevalence (4.76%) was recorded in 51 - 58 cm length group and the lowest (2.63%) observed in the smallest length group (35 – 42

207 cm). The intensity (1 ± 0) was recorded in the smallest length group (35 – 42 cm) and 51 - 58 cm length group.

The food items found in the stomach of W. attu and R. rita were divided into five basic categories: fish, crustaceans, insects, molluscans and plants. Among the animal foods, the most important and most frequent were the small fishes (Amblyphryngodon mola, Corica sp. etc.) which comprised the greatest proportion of the fish diet of W. attu. The occurrence of small fish item was 27.2% in W. attu and 18.3% in R. rita. The frequency of consumption of small fishes maintained the relationship of increasing the tendency from small to larger size of fishes of both species.

The occurrence of crustacean (prawns, small crabs, Cyclops, Diaptomas etc.) food items was higher (17.6%) in W. attu than in R. rita (4.8%). In W. attu, in both the years, there was a similar sequential pattern in the peaks of the frequency curves. In R. rita, the peaks were prominent in August 2011 (12.5%) and lower frequency (5.8%) was observed during the month of February 2011.

Among the additional food items, the insects occurred 5.2% and mollusks 3.2% in W. attu, while in R. rita, they were 3.1% and 18% respectively. Some aquatic plants and algae were also found as incidental food item but in a very negligible frequency in the stomach of both the species of fish.

The analyzed results of nutritional components in two species of fish revealed that, the moisture content was higher in W. attu (74.48 g / 100g) than in R. rita (73.61 g / 100 g) whereas, the percentage of protein and fat contents were higher in R. rita (16.45 g / 100 g and 5.51 g / 100 g) than in W. attu (15.28 g / 100 g and 2.34 g / 100 g respectively).

The contents of biochemical nutritional components (moisture, protein, fat, carbohydrate and ash) of non-infected fishes were found quite higher than infected fishes (in both host species). Due to the massive tissue destruction by trematode I. hypselobagri in W. attu, the loss of nutritional components were remarkable. The

208 structural integrity of the visceral organs and body musculature of W. attu were massively disrupted by enteric parasites. In the present study, juvenile Isoparorchis hypselobagri was the most pathogenic and damaging of the whole. The extent of damage done by I. hypselobagri was highly variable but was related to intensity of infection and of the size of the host and parasites. With the help of penetrating glands, located in the oral sucker, the juvenile trematode dissolved the skin and muscles for making the tunnel or space in the host tissues, resulting accumulation of melanin macrophages and more moisture, necrosis, connective tissue proliferation and mixed inflammatory responses.

Heavy melanin deposition was observed along with accumulated melanin macrophage centers in the infected liver. Sometimes hepatic blood vessels were ruptured with mild hepatic or hemopoietic degenerative changes with hemorrhages. The intestinal wall was heavily destroyed. Fluid filled empty space along with debris and lymphocytes were present. The intestinal mucosa and villi tissue showed incipient necrosis. During the migration of immature I. hypselobagri from cavity to the swim bladder, massive disruption and dislocation of the visceral organs occurred. Irregular black pigmentation was scattered throughout the swim bladder, in severe cases, the alveolar sacs and capillary plexuses were disrupted causing necrosis.

In Rita rita, the highest temperature (28.72 ◦ C and 28.8 ◦ C) and highest prevalence (95.4% and 42.6%) were recorded during rainy season in 2011 and 2012 both. The lowest average temperature (20.75 ◦ C and 20.72 ◦ C) was recorded during winter in 2011 and 2012 while the lowest prevalence (80.6% and 28.9%) was observed during summer in 2011 and 2012. The prevalence was found negatively correlated with temperatures (r = - 0.53). In W. attu, in 2011 and 2012 , the highest temperature (28.72 ◦ C and 28.8 ◦ C) were recorded during rainy season and the highest prevalence (45.2% and 30.2%) were found during winter. The lowest temperature (20.75 ◦ C and 20.72 ◦ C) was recorded during winter in 2011 and 2012 while the lowest prevalence (38.1%) was observed during summer in 2011 and 24.4% during rainy season in 2012. The prevalence was negatively correlated with temperatures (r = - 0.49).

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In W. attu, in 2011 and 2012 , the highest total rainfall (271 mm and 156.75 mm) were recorded during rainy season and the highest prevalence (45.2% and 30.2%) were found during winter. The lowest total rainfall (0 mm and 21 mm) was recorded during winter in 2011 and 2012 while the lowest prevalence (38.1%) was observed during summer in 2011 and 24.4% during rainy season in 2012. In Rita rita, the highest rainfall (271 mm and 156.75 mm ) and highest prevalence (95.4% and 42.6%) were recorded during rainy season in 2011 and 2012 both. The lowest rainfall ( 0 mm and 21 mm) was recorded during winter in 2011 and 2012 while the lowest prevalence (80.6% and 28.9%) was observed during summer in 2011 and 2012.

In Wallago attu, in 2011 , the highest humidity (99%) were observed in the month of Jan’11 and lowest humidity was 93% found in Feb’11, Mar’11 and April’11 while the highest prevalence (72.72%) were observed in the month of Dec’11 and the lowest prevalence was 30% in Feb’11, May’11 and Aug’11. In 2012, the highest humidity (100%) was found in July’12 and lowest (92%) observed in Feb’12 while the highest prevalence (44.44%) recorded in Feb’12 and the lowest was 18.18% in Sep’12 and Nov’12. The prevalence was positively correlated with humidity (r = 0.46) in different months. In Rita rita, in 2011 , the highest humidity (99%) were observed in the month of Jan’11 and lowest humidity was 93% in Feb’11, Mar’11 and April’11 while the highest prevalence (100%) were observed in the month of July’11 and lowest prevalence was 73.68% in Jan’11. In 2012, the highest humidity (100%) was found in July’12 and lowest (92%) observed in Feb’12 while the highest prevalence (57.14%) recorded in July’12 and lowest was 16.66% in May’12. The prevalence was positively correlated with humidity (r = 0.51) in different months.

From the results and records of the present study, it can be conclude that, though the feeding habits and habitat of both the species were similar, W. attu was found to be infected by comparatively a large community of parasites. So, it can be assumed that, W. attu is more susceptible for helminth infections than R. rita.

Considering the parasitic problems in the fish, it is necessary to conduct different studies on aspects of biology related to nutritional values and parasitic infections of W. attu and R. rita to help the production of worm free fishes in our country.

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BIBLIOGRAPHY

Adhikari, S. and Noor, A. 1967. Seasonal variation in oil, water contents and solid matters in different organs of punti fish. Sci. Res. 4: 55 – 63. Agarwal, L.N. and Agarwal, G.P. 1984. On a new digenetic trematode Oudhia kanungo n. sp. from the intestine of a freshwater fish Rita rita. Rivista-di-Parasitologia. 1 (45): 1: 231 – 234. Agarwal, V. and Sharma, R. 1988. A rare monogenean Hamatopeduncularia lucknowensis from a silurid fish, W. attu at Lucknow. Japanese Journal of Parasitology. 37: 6, 373 – 375. Agarwal, S.C. and Sharma, S.K. 1989. Nicolla fotedari sp. nov. from a fresh water fish Rita rita from Jhansi. Ind. J. Helminthol. 41: 2: 100 – 103. Ahmad, J. 1984. Studies on digenetic trematodes from fresh water fishes of India. Part.1. On four new species of the genus Satyapalia Rivista- di-Parasitologia. 1(45): 11 – 17. Ahmed, A.T.A and Rahman, M.S. 1976. Some aspects of the biology of some metazoan parasites in Indian halibut (Psettodes erumei) and large scaled tonguesloe (Cynoglossus macrolepidotus) from the Bay of Bengal. J. Asiat. Soc. Bangladesh. 2 (1): 63 – 73. Ahmed, A.T.A and Sanaullah, M. 1976. Organal percentage of distribution of some metazoan parasites in Heteropneuates fossilis and Clarias batrachus. J. Asiatic Soc., Bangladesh (Sc.). 2 (1): 7 – 15. Ahmed, A.T.A. and Sanaullah, M. 1976. Observation on the incidence and intensity of some helminth in different length groups of Heteropneuates fossilis and Clarias batrachus. Dhaka Univ. Studies. Part B, 15 (2): 91 – 98. Ahmed, A. T. A. and Rahman, M. S. 1977. Distribution of some nematode and crustacean parastites in Psettodes erumei and Cynoglossus macrolepidotus in the Bay of Bengal. J Asiatic Soc Bangladesh (Sci). 2: 7 – 14. Ahmed, A.T.A. and Sanaullah, M. 1977. „Studies on the distribution of metazoan parasites of Heteropneuates fossilis and Clarias batrachus in Bangladesh‟. Bangladesh J. Zool. 5 (2): 117 – 123.

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Ahmed, A.T.A and Begum, R. 1978. Studies on the distribution of some endoparasitic helminths in six freshwater fishes of Dhaka and Barisal. Bangladesh J. Aquac. 1 (1): 52 – 60. Ahmed, A.T.A. and Sanaullah, M. 1978. Observation in the infections in catfishes, H. fossilis and C. batrachus. Bangladesh Jour. Fish. 1: 73 – 94. Ahmed, A.T.A and Rahman, M. S. 1979. Pathogenecity of some nematodes in flatfish. Bangladesh J. Agri. 4 (1): 89 – 93. Ahmed, A.T.A. and Sanaullah, M. 1979. Pathological observations of the intestinal lesions induced by caryophyllid cestodes in C. batrachus. Fish Path. (Japan).14(1): 1 – 7. Ahmed, A.T.A., Mustafa, G. and Hai, A. 1980. Food and feeding habits of catfish Clarias Batrachus. Dhaka Univ. Studies. B. 18 (2): 79 – 84. Ahmed, A. T. A. 1981. Helminth infection in freshwater fishes of Bangladesh. Fish Pathol. 15: 229 – 236. Ahmed, K. and Hassan, N. 1981-1982. Nutrition survey of Rural Bangladesh. Institute of Nutrition and Food Science, University of Dhaka. 32 – 37 pp. Ahmed, A. T. A. and Rouf, A. J. M. A. 1982. Acanthocephalan parasites of freshwater and estuarine fishes of Bangladesh. Proc 3rd Nat Zool Conf. 1981 Dacca. 118 – 125 pp. Ahmed, A. T. A., Roy, P. and Mustafa, G. 1984. Organal distribution of some cestode parasites and their percentage of infection in two catfishes. J Asiatic Soc Bang (Sci). 10: 1 – 6. Ahmed, A.T.A., Mustafa, G. and Roy, P. 1985. Organal distribution of some caryophyllid parasites and their seasonal fluctuation in the gut of two freshwater cat fishes. Bangladesh J. Agri. 10 (2): 59 – 63. Ahmed, N. 2008. Management of storm water for drainage of Azimpur, BUET and Lalbag Area of Dhaka City. M.Sc. Thesis, Institute of Water and Flood Management, BUET. Ahmed, S., Rahman, A. F. M. A., Mustafa, M. G., Hossain, M. B. and Nahar, N. 2012. Nutrient composition of indigenous and exotic fishes of rainfed waterlogged paddy fields in Lakshmipur, Bangladesh. World J. Zool., 7: 135 – 140.

212

Aho, J. M., Camp, J. W. and Esch, G. W. 1982. Long-term studies on the population biology of Diplostomulum scheuringi in a thermally altered reservoir. J. Parasitol. 68: 695 – 708. Akhtar, H. K., Chowdhury, A., Latifa, G. A. and Nahar, N. 1989. Observation of helminth infection in relation to seasons and body length of X. cancila J. Asiatic. Soc. Bangladesh (Sc.). XV(1): 37 – 42. Akhtar, H. K., Sufi, G. B. and Nahar, N. 1990. Incidence of helminth parasites in X. cancila in relation to food items. Bangladesh, J. Sci. Res. 8 (2): 173 – 179. Akhtar, M., D'Silva, J. and Khatun, A. 1997. Helminth parasites of Anabas testudeneus in Bangladesh. Bangladesh J Zool. 25: 135 – 137. Alam, M. R. 2006. Endoparasitic helminths in Notopterus notopterus in Bangladesh. Bang. J. Life Sci.,2006. 18 (2): 51 – 57. Ali, M.Y. 1968. Investigation of fish diseases and parasites in East Pakistan Bull. Off. Inter. Epiz. 69 (9-10): 1517 – 1521. Ali, M., Day, P. C., Islam, A. and Hanif, M. A. 1985. Food and feeding habits of Pangasius pangasius of the river Bishkhali, Patuakhali. Bangladesh, J. Zool. 13 (1): 1 – 6. Ali, M., Igbal, F., Salam, A., Iram, S. and Athar, M. 2005. Comparative study of body composition of different fish species from brackish water pond. Int. J. Environ. Sci. Technol. 2: 229 – 232. Allan, R. P. and Soden, B. J. 2008. Atmospheric warming and the amplification of precipitation extremes. 321 (5895): 1481 – 1484 pp. Amin, O. M. 1975. Host and seasonal associations of Acanthocephalus parksidei in Wisconsin fishes. Journal of Parasitology. 61: 318 – 327. Anderson, R. M. 1976. Seasonal variation in the population dynamics of Caryophyllaeus luticeps. Parasitology, 72: 28 – 395. Angeloupalo, V. 1947. The anatomy of Clarias gariepinus. M.Sc. Thesis, University of Pretoria.76 pp. Arctic Council 2005. Arctic climate impact assessment (Cambridge Univ Press, Cambridge, UK)

213

Arthur, J. R., Margolis, L., Whitaker, D. J. and McDonald, T. E. 1982. A quantitative study of economically important parasites of Walleye Pollock (Theragra chalcogramma) from British Columbian waters and effects of postmortem Handling on their abundance in the musculature. Can. J. Fish. Aquat. Sci. 39: 710 – 726. A.O.A.C. 1975. Official Methods of Analysis: Association of official agricultural chemists. 12th ed. Washington, D.C. 832 pp. Ashrafuddin, M. 1977. Studies in some helminth parasites from five species of commercially valuable fishes of the Bay of Bengal. M. Sc. Thesis, Department of Zoology, University of Dhaka. 74 pp. Awachi, J. B. E. 1968. On thr bionomics of Crepidostomum metoecus and Crepidostomum farionis. Parasitology. 58: 307 – 324. Azam, K., Ali, M. Y., Asaduzzaman, M., Basher, M. Z. and Hossain, M. M. 2004. Biochemical assessment of selected fresh fish. J. Biological Sci. 4 (1): 9 – 10. Azim, M. A., Islam, M. R., Hossain, M. B. and Minar, M. H. 2012. Seasonal variations in the proximate composition of gangeticsillago, Sillaginopsis panijus, Middle-East. J. Sci. Res. 11: 559 – 562. Bailey, N. T. J. 1959. Statistical methods in Biology. The English Uni. Press Ltd. London EC4. 200 pp. Banu, C. P., Sultana, S. and Salamatullah, Q. 1991. Studies on the mineral contents of freshwater fish and meat. Beng. J . Zool. 19 (1): 59 – 63. Banu, A. N. H., Khan, M. H., Hossain, M. A. and Azim, M. E. 1999. Parasitic diseases of freshwater fish in nursery operation system of Bangladesh, Abstract. No 61. In Book of Abstract. Fourth Symposium on Diseases in Asian Aquaculture, "Aquatic Animal Helath for Sustainabulity". Cebu International Convocation Centre, Cebu City, Philippines. Fish Helath Section, Asian Fisheries Society. Bashirullah, A. K. M and Islam, M. A. 1970. A new phyllodistome from the swim bladder of Siluroid fish. Pakistan. J. Zool. 2 (1): 25 – 27. Bashirullah, A. K. M. 1972. On the occurrence of the trematode, Isoparorchis hypselobagri in fishes and notes on its life history. Norwegian J Zool. 20: 209 – 212. Bashirullah, A. K. M. 1972 a. On the occurrence of the trematode Isoparorchis hypselobagri is the fishes and notes on its life history. Norw. J. Zool. 20: 209 – 212. 214

Bashirullah, A. K. M. 1972 b. On the occurrence of G. spinigerum in the vertebrates. Bangladesh. J. Parasit. 58: 187. Bashirullah, A. K. M. and Elahi, K. M. 1972a. On two new two species of Genarchopsis from freshwater fishes of Daca, Bangladesh. Riv Di Parassit. 33: 277 – 280. Bashirullah, A. K. M. and Elahi, K. M. 1972b. Three trematodes (Allocreadiidae) from the freshwater fishes of Dacca, Bangladesh. Norwegian J Zool. 20: 205 – 208. Bashirullah, A. K. M. 1973. A brief survey of the helminth fauna of Certain marine and freshwater fishes of Bangladesh. Bang. J. Zool. 1 (1): 63 – 81. Bashirullah, A. K. M. 1974 a. Notes on Spirocamallanus olseni. Am Nat 92: 256 pp. Bashirullah, A. K. M. 1974 b. Two new nematode species of Camallanus from freshwater fishes of Dacca, Bangladesh. Norwegian J Zool. 22: 57 – 60. Bashirullah, A. K. M. and Hafizuddin, A. K. M. 1973. Two nematode species of procamallanidae from freshwater fishes of Bangladesh. Rivista parasitol. 34: 115 – 119. Bashiruulah, A. K. M. and Hafizuddin, A. K. M. 1974. Two new nematode species of Procamallanus from fishes of Dacca, Bangladesh. Norwegian J Zool. 22: 53 – 55. Bashirullah, A. K. M. and Ahmed, B. 1976 a. Development of Camallanus adamsi in cyclopoid copepods. Can J Zool 54: 2055 – 2060. Bashirullah, A. K. M. and Ahmed, B. 1976 b. Larval development of Spirocamllanus intestinecolas in copepods . Riv Di Parassitol. 37: 303 – 311. Bashirullah, A. K. M. and Hafizuddin, A. M. M. 1976. Digenetic trematodes from freshwater fishes of Bangladesh. Riv Di Parassit. 37: 35 – 39. Bashirullah, A. K. M. 1974. Two new nematode species of Procamallanus from freshwater fishes Dhaka, Bangladesh. Norw J. Zool. 22 (1): 53 – 55. Bauer, O. N. 1959. The ecology of parasites of freshwater fish. In: Parasites of freshwater fish and the biological basis for their control. Bulletin of the state Scientific Research Institute of Lake and River fisheries, Jerusalem, 1962. 45: 3 – 215. Baum, J. K. and Worm, B. 2009. Cascading top-down effects of changing oceanic predator abundances. J Anim. Ecol. Baur, O. 1962. Parasites of freshwater fish and the biological basis for their control. Bulletin of the State Scientific Research Institute of Lake and River Fisheries. XLIX: 108 – 112.

215

Baylis, H. A. 1939. Nematoda, Vol. II (Ascaroidea and Strongyloidea). Fauna of British India, including Ceylon and Burma. 408 pp. Begum, M. M. and Chandra, K. J. 2003. Investigation on monogenetic trematodes of Mystus vittatus, Ailia coila and Esomus danricus of Mymensingh. J. Bangladesh Agril. Univ. 1 (1): 87 – 98. Benazir, A. 1989. Study on helminth infestation and some biological aspects of Mystus vittatus, M. cavasius and M. tengra, M.Sc. Thesis, Dept. of Zool. Univ. Dhaka. 142 pp. Benmansour, B. 1995. Analyse de la biodiversité des copépodes parasites du secteur Nord-Est de la Tunisie. DEA de parasitologie fondamentale et appliquée. Faculté des Sciences de Tunis. 217 pp. Benmansour, B. and Ben hassine, O. K. 1997. Première mention en Tunisie de certains caligidiae et lernaeopodidae (Copepoda) parasites de poissons Téléostéens. Acta Ichtyophysiologica, 20: 157 – 175. Benmansour, B. and Ben hassine, O. K. 1998. Preliminary analysis of parasitic copepod species richness among costal fishes of Tunisia. Ital. J. Zool. 65: 341 – 344. Benmansour, B. 2001. Biodiversité et bio-écologie des copépodes parasites de poissons Téléostéens. Thèse de doctorat en biologie. Faculté des Sciences de Tunis, 453 pp. Bhadauria, S. and Dandotia, M. R. 1984. Studies on the trematode parasites of fresh water fishes with special references to Gualior Region. Part II. On one new genus and some unknown and known species. Riv-di-Parasitol. 1(45): 2: 341 – 383. Bhaduria, S. and Dandatia, M. R. 1986. Studies on the digenetic trematodes of freshwater fishes with special ref. to Gwalior region. Part IV. Description of 10 new and six already known forms belonging to 8 genera of trematodes. Bucephalus gwaliorensis, B. attuai, Opisthorchis pedicellata (new host record) and Phyllodistomum spatulaeformae from W. attu from Gwalior, M.P, India. Rivista-di- parasitologia. 3 (47): 3, 353 – 397. Bhalerao, G. D. 1932. A note on the probability of infection of man and domestic carnivores by I. hypselobagri. Indian J. Vet. Sci. Anim. Husb. II (IV): 404 – 405. Bhattacharjees, R. 1986. Studies on Caryophyllidean cestode parasites of some catfishes and histopathology of the host. The North eastern Hill Univ. Shillong, India. 2: 103 – 115. 216

Bolock, A. R. and Koura, R. 1959. Observations on age, growth and feeding habits of Clarias lazera in barrage experiment ponds. Notes and memories, Hydrobiological Department, Ministry of Agriculture, UAR, 56: 17 pp. Bovien, P. 1926. Caryophyllaeidae from Java Meddelelser fra Dansk naturchistorisk Forening L. koben hunn. 82: 157 – 181. Brander, K. M., Blom, G., Borges, M. F., Erzini, K., Henderson, G., MacKenzie, B. R., Mendes, H., Ribeiro, J., Santos, A. M. P. and Toresen, R. 2003. Hydrobiological variability in the ICES area, 1990–1999, eds Turrell, W., Lavin, A., Drinkwater, K. F., St John, M. A., Watson, J. Intl Council for the Exploration of the Sea, Copenhagen. 261 – 270 pp. Brander, K. M. and Mohn, R. K. 2004. Can J Fish Aquat Sci. 61: 1558 – 1564. Bullock, W. L. 1963. Intestinal histology of some salmonid fishes with particular reference to histopathology of acanthocephalan infections. J. Morph. 112: 23 – 44. Cable, R. M.1963. An illustrated laboratory manual of parasitology. Burges Publishing Company. Minneapolis, U.S.A. 169 pp. Camp, J. W., Aho, J. M. and Esch, G. W. 1982. A long-term study on various aspects of the population biology of Ornithodiplostomum ptychocheilus in a South Carolina cooling reservoir. J. Parasitology. 68: 709 – 718. Cannon, L. R. G. 1973. Diet and intestinal helminthes in a population of perch, Perca flavesens. J. Fish. Biol. 5: 447 – 457. Chakravarty, R. and Tandon, V. 1988. Caryophylliasis in the cat fish, Clarias batrachus: some histopahological observations. Proceedings of the Indian Academy of Sciences (Animal Sciences), 21 (2): 127 – 132. Chakravarty, R. and Tandon, V. 1989. Histochemical studies on Lytocestus indicus and Djombangia penetrans, caryophyllidean cestode parasites of Clarias batrachus. Helminthologia. 26: 259 – 272. Chakrabarty, S. C., Uddinand, M. B. and Islam, M. N. 2003. A study on the composition of common freshwater fishes of Bangladesh. Bangla. J. Fish. 26: 23 – 26. Chandra, K. J. 1983. A note on the metacercaria of Euclinostomun multicaecum from freshwater fishes of Bangladesh, Bangladesh J Aquacult. 25: 91 – 93. Chandra, K. J. 1984. Nature of Biclinostomum multicacum infestation in Channa punctatus. Bangladesh J. Zool. 18 (1 – 14): 49 – 54.

217

Chandra, K. J. 1985. Incidence and intensity of infestation of Pallisentis ophicephali on the host C. punctatus . Jour. Asiatic. Soc. of Bangladesh. (SC.). Vol. XI (1): 47 – 54. Chandra, K. J. and Rahman, M. A. 1988. A new host record for Pallisentis ophiocephali. Indian J Parasitol. 12: 37 – 38. Chandra, K. J. 1992 a. Studies on the helminth parasites, infections and diseases of some freshwater and estuarine fishes of Bangladesh. BAU Res Prog. 6: 402 – 408. Chandra, K. J. 1992 b. Records of nematode parasites of freshwater fishes of Indian subcontinent. Proc First Ann Conf, Bangladesh Soc Parasitol. 52 – 71 pp. Chandra, K. J. 1993. Helminth parasites of certain freshwater and marine fishes of Bangladesh. BAU Res Prog. 7: 543 – 554. Chandra, K. J. and Banerjii, M. 1993 a. Digenetic trematodes from freshwater fishes of Mymensingh. Riv Di Parasitol. 54: 81 – 91. Chandra, K. J. and Banerjii, M. 1993 b. Three digenetic trematode parasites from freshwater fishes of Mymensingh. Riv Di Parassitol. 54: 71 – 79. Chandra, K. J. and Khatun, M. R. 1993. A new species of caryophyllid cestode from Heteropneustes fossilis of Mymensingh. Riv Di Parassitol. 54: 235 – 239. Chandra, K. J. 1994. Infections, concurrent infections and fecundity of Procamallanus heteropneustus, parasitic to the fish Heteropneustes fossilis. Environ Ecol. 12: 679 – 684. Chandra, K. J. and Modak, P. C. 1995. Activity, ageing and penetration of the first stage larvae of Procamallanus heteropneustus. Asian Fish Sci. 8: 95 – 101. Chandra, K. J., Begum, A. A., Ahmed, G. U. and Wootten, R. 1996 b. Infection of Myxosporean ecto-parasites of juvenile carps in nurseries of Mymensingh Bangladesh. Bangladesh J Aquacult. 18: 39 – 44. Chandra, K. J., Islam, M. Z. and Wootten, R. 1997. Some aspects of association and development of Lytocestus indicus in Catfish Clarias batrachus. Bangladesh J Fish Res. 1: 31 – 38. Chandra, K. J., Mohanta, S. K., Hossain, M. M., Nahar, S., Yasmin, R. and Paul, S. K. 2000 a. A study on the prevalence of monogenetic ectoparasites of freshwater fishes. BAU Res. Prog. 11: 134 – 143.

218

Chandra, K. J., Paul, R. K. and Islam, M. A. 2000 b. Monogenean ectoparasites of Wallago attu in freshwater fishes of Mymensingh, Bangladesh. Bangladesh J Agric. 25: 2000 pp. Chandra, K. J. and M. S. Jannat, M. S. 2002. Monogenean gill parasites of manor carps from different fish farms of Mymensingh. Bangladesh J Fish Res. 6: 43 – 52. Chandra, K. J. and Yasmin, R. 2003. Some rare and new monogenetic trematodes from air-breathing freshwater fishes of Bangladesh. Indian J Anim Sci. 73: 113 – 118. Chandra, K. J. 2006. Fish parasitological studies in Bangladesh: A review. J Agric Rural Dev. 4 (1 and 2): 9 – 10. Chandra, K. J. and Yasmin, R. 2003. Some rare and new monogenetic trematodes from air breathing freshwater fishes of Bangladesh. Indian Journal of Animal Sciences. 7(1): 113 – 118. Chauhan, B. S. and Ramakrishna, G. 1958. On the occurrence of the fish mortality due to helminthic infestation by cestode cysts in a stocking tank at Nagpur (India). Indian J. of Helminthology. 10 (1): 53 – 55. Cheng, T. C. 1964. The biology of animal parasites. W.B. Saunders company, Philadelphia and London, Toppan Co. Ltd., Tokyo, Japan. 369, 441,727 pp. Chubb, J. C. 1977. Seasonal occurrence of helminthes in fresh water fishes. Part I. Monogenea. In Advances in Parasitology (B. Dawes, ed.). Academic Press, London, New York. 15: 133 – 243. Chubb, J. C. 1979. Seasonal occurrence of helminthes in fresh water fishes. Part II. Trematoda. In Advances in Parasitology (W. H. R. Lumsden, R. Muller and J. R. Baker, eds). Academic Press, London, New York. 17: 141 – 313. Chubb, J. C. 1980. Seasonal occurrence of helminthes in fresh water fishes. Part III. Larval Cestoda and Nematoda. In Advances in Parasitology (W. H. R. Lumsden, R. Muller and J. R. Baker, eds). 18: 1 – 120. Chubb, J. C. 1982. Seasonal occurrence of helminthes in fresh water fishes. Part IV. Adult Cestoda, Nematoda and Acanthocephala. In Advances in Parasitology (W. H. R. Lumsden, R. Muller and J. R. Baker, eds). Academic Press, London, New York. 19: 1 – 293. Chowdhury, M. B. R., Haque, A. K. M. and Islam, M. A. 1982. Incidence of diphyllobothriid larva and Pallisentis nandai in Nandus nandus fish. Bangladesh J Agricult Sci. 9: 191 – 197. 219

Chowdhury, A., Khanum, H. and Begum, S. 1986. I. hypselobagri, its abundance and intensity of infestation in the host Mystus vittatus. Bangladesh J. parasitol. 61:108 – 112. Chowdhury, A. K. 1992. Helminth parasites infestation and histopathological changes in Snakehead fishes. M.Sc Thesis, Dept. of Zool., Eden Univ. College, Dhaka. Chowdhury, M. B. R. 1993. Research priorities for microbial fish and its control in Bangladesh. In “Research Priorities in Bangladesh for Fish Health, Disease Prevention and Pathology” (Tollervey, Ed.), A one-day ODA/BAU workshop held at the Faculty of Fisheries, BAU, Mymensingh. 8 – 11 pp. Clay, D. 1979. Population biology, growth and feeding of African catfish with special reference to juveniles and their importance in fish culture. Arch. Hydrobiol. 87(4): 453 – 482. Coley, P. D. and Aide, T. M. 1991. Comparison of herbivory and plant defenses in temperate and tropical broad-leaved forests. In: Price, P.W., Lewinsohn, T.M., Fernandes, G.W., Benson, W.W. (Eds.), Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions. Wiley and Sons, New York, 25 – 49 pp. Combes, C. 1995. Interactions durables: Ecologie et évolution du parasitisme. (Ed) Masson, Paris: 1 – 524 pp. Cribb, T. H. 1988. Two new digenetic trematodes from Australian fresh water fishes with notes on previously described species. J. of Natural history. 22: 27 – 43. Cui, Y. and Wootton, R. J. 1988. Effects of ration, temperature and body size on the body composition, energy content and condition of the minnow, Phoxinus phoxinus. J. Fish Biol., 32: 749 – 764. Das, M. and Moitra, X. 1955. Studies on the food of some common fishes of Uttar Pradesh, India. Part I. Surface feeders, mid-feeders and bottom feeders. Proc. National Acad. Sci. India. 25 (1 – 11): 1 – 6. Datta, N. B. 1971. Studies on the digenetic trematodes and nematodes of some freshwater fishes of Dacca. M.Sc. Thesis, Department of Zoology, University of Dhaka. 89 pp. Day, F. 1878. The fishes of India. A natural history of the fishes of India, Burma and Ceylon. London. 1 (I – XX): 1 – 816. Day, F. 1889. Fauna of british india fishes. Frasicies and Taylor, London. 509 pp.

220

De, N. C. 1989. Morphology of Cucullanus ritai and remarks on the validity of the genus Paracucullanellus and its type species. Folia. Parasitologica. 36: 153 – 160. Devaraj, M and Ranganathan, V. 1971. Incidence of I. hypselobagri among the catfishes of Bhavanisagar reservior. Indian Jour. Fishery. 14 (1): 232 – 250. Devi, R. P. 1973. Lytocestus longicollis sp. nov. from the cat fish Clarias batrachus in India. Journal of Helminthology. 47 (4): 415 – 420. Djait, H. 2009. les macro-ectoparasites des Sparidés et Mugilidés dans la lagune de Bizerte et Ghar El Melh. Mémoire de mastère. Institut Supérieur de Biothechnologie de Monastir. 174 pp. D'Silva, J. and Khatun, S. M. 1997. Helminth parasites of two clupeid fishes from the Bay of Bengal, Bangladesh J Noami. 14: 27 – 37. Dobson, A. P. 1985. The population dynamics of competition between parasites. Parasitology. 91 (2): 317 – 347. DoF, 2010. Saranica, matsya pakhya sankalan. Ministry of Fisheries and Livestock, The Government of Peoples Republic of Bangladesh. Dogiel, V. A. 1961. Ecology of the parasites of fresh water fishes. In Parasitology of Fishes. Edited by V. A. Dogiel, G. K. Petrushevski and YU. I. Polyanski. (English translation Z. Kabata). Oliver and Boyd. Edinburgh. 1 – 47 pp. Dogiel, V. A. 1964. General parasitology. Leningrad Univ. Press (English translation Z. Kabata). Oliver and Boyd. Edinburgh. 516 pp. Drinkwater K. F. 2005. ICES (Intl Council for the Exploration of the Sea). J Mar Sci. 62: 1327 – 1337. Drury, R. A. B and Wallington, E. A. 1967. Carlenton histological technique, 4th ed. Oxford University Press, New York. Duggal, C. L. and Bedi, H. 1987. On one new and four already known species and sub species of Opisthorchis infecting freshwater fishes of Punjab, India. O. pedicellata was found for the first time in the intestine of W. attu. Rivista-di- parasitologia. 4 (48): 2, 145 – 150. Dzika, E. 2002. The parasites of bream Abramis brama from Lake Kortowskie. Archives of Polish Fisheries, 10: 85 – 96. Eduardo, S. L., Manalo, V. C., Tayag and Kaw, M. C. 2001. New records and previously known helminth parasites of the catfish and mudfish in Laguna Lake, Philippine. Journal of Veterinary Medicine. 38 (2): 110 – 111. 221

Elahi, M. 1969. Studies on the endoparasites of the family Channidae. M.Sc. Thesis, Department of Zoology, University of Dhaka. 102 pp. Elliot, J. M. 1979. Some methods for statistical analysis. Fresh water Biological Association. 1 – 56. Esch, G. W. and Huffines, W. J. 1973. Histopathology associated with endoparasitic helminthes in Bass. The J. of Parasitology. 59 (2): 306 – 313. Esch, G. W. 1983. The population and community ecology of cestodes. In The Biology of Cestodes (P. Pappas and C. Arme, eds.). Academic Press, New York. 216 pp. Essafi, K., Cabral, P. and Raibaut, A. 1984. Copépodes parasites de poisons des iles Kerkennah (Tunisie méridionale). Archs. Inst. Pasteur Tunis, 61 (4): 475 – 523. Evans, N. A. 1977. The site preference of two digeneans, Asymphylodora kubanicum and Aphaerostoma bromae in the intestine of the roach. Jour. of Helminthology. 51: 197 – 204. Farhana, R. and Khanum, H. 2013. Helminth parasites of Mystus aor and Mystus bleekeri in Bangladesh. J. Natural History. 8 (2): 65- 75. Fawole, O. O., Ogundiran, M. A., Ayandiran, T. A. and Olagunju, O. F. 2007. Proximate and mineral composition in some selected fresh water fishes in Nigeria. Internet J. Food Saf. 9: 52 – 55. Ferdousi, U. K. and Chandra, K. J. 2002. Monogenean gill parasites of Oreochromis niloticus and Oreochromis mossambicus from Mymensingh, Bangladesh. Riv Di Parassit. 64: 49 – 60. Ficke, A. D., Myrick, C. A. and Hansen, L. J. 2007. Potential impacts of global climate change on freshwater fisheries. Reviews in Fish Biology and Fisheries. 17 (4): 581 – 613. Fischthal, J. H. and Robert, E. K. 1963. Trematode parasites of fishes from Egypt. Part vii. Orientocreadium batrachoides from Clarias lazera, with a review of the genus and related forms. Jour. Parasitology. Vol. 49 (3): 451 – 464. Forbes, A. 1888. On the food relation of fresh water fishes. A summary and discussion, Bull. III. St. Lab. Nat. Hist. 2 pp. Friedland, K. D., Reddin, D. G., McMenemy, J. R. and Drinkwater, K. F. 2003. Can J Fish Aquat Sci. 60 : 563 – 583. Froese, R. and Pauly, D. 2010. Fish Base. World wide web electronic publication. www.fishbase.org, version (01/2010).

222

Frost, W. E. 1946. On the food relationships of the fish in Windermere. J. Anim. Ecol. 13: 216 – 231. Frost, W. E. 1954. Food of the pike, Esox lucius L. in Windermere. J. Anim. Ecol. 23: 339 – 360. Fung, C. F., Farquharson, F. and Chowdhury, J. 2006. Exploring the impacts of climate change on water resources-regional impacts at a regional scale: Bangladesh. Climate Variability and Change- Hydrological Impacts (Proceedings of the 5th FRIEND World Conference held at Havana, Cuba, November 2006), IAHS Publication, 308, 389 – 393 pp. Furtado, J. I. 1963. A new caryophyllaeid cestode, Lytocestus parvulus sp. nov. from a malayan catfish. Ann. Mag. Nat. Hist. London. Vol. 6, 62: 97 – 106. Furtado, J. I. and Tan, K. L. 1973. Incidence of some helminth parasites in the malaysian cat fish, Clarias batrachus. Verb. Internat. Vereun. Limnol. 18: 1674 – 1985. Galli, P., Crosa, G., Mariniello, L., Ortis, M and D‟Amelio, S. 2001. Water quality as a determinant of the composition of fish parasite communities. Hydrobiologia. 452: 173 – 179. Gheyasuddin, S., Rahmanand, A. and Mumtazuddin, M. 1979. Biochemical composition of shellfishes of Bangladesh. Bangla. J. Sci. Res. 2: 15 – 23. Ghosh, P. K., Chandra, K. J. and Saha, P. K. 2003. Monogenean intestation in indigenous small fishes of Bangladesh. Riv Di Parassit 64:189–201. Giri, S. S., Sahoo, S. K., Sahu, B. B., Mohanty, S. N., Mukhopadhyay, P. K. and Ayyappan, S. 2002. Larval survival and growth in Wallago attu; effects of light, photoperiod and feeding regimes. Aquaculture. 213: 151 – 161. Golder, M. I. and Chandra, K. J. 1987. Infestation of Isoparorchis hypselobagri on the host fish Nandus nandus. Environ Ecol. 5: 337 – 341. Golder, M. I., Chandra, K. J. and Rahman, A. K. A. 1987. Helminth parasitism in Nandus nandus. Bangladesh J Fish 10: 11 – 22. Gopalan, C. 1971. A manual of laboratory techniques. National Institute of Nutrition, Hydrabad, India. 60 – 148 pp. Goswami, P. K. and Devraj, M. 1992. Breeding, age and growth of the freshwater shark Wallago attu from the Dhir Beel of the Brahmaputra basin, Assam, India. J. Indian Fish. Assoc. 22: 13 – 20.

223

Granath, W. O. and Esch, G. W. 1983 a. Seasonal dynamics of Bothriocephalus acheilognathi in ambient and thermally altered areas of a North Carolina cooling reservoir. Proc. Helminthol. Soc. Wash. 50 (2): 205 – 218. Granath, W. O. and Esch, G. W. 1983 b. Temperature and other factors that regulate the composition and infrapopulations densities of Bothriocephalus acheilognathi in Gambusia affinis. J. Parasitol. 69: 1116 – 1124. Gray, P. 1964. Handbook of basic microtechnique. 3rd edi. McGraw Hill Book Company, New York. 302 pp. Gupta, S. P. 1951. Trematode parasites of indian fishes. Three new trematodes of the subfamily leptophallinae from freshwater fishes of U.P. Indian J. Helminths. 3 (1): 29 – 40. Gupta, S. P. 1953. Trematode parasites of freshwater fishes. Indian J. Helminths. Vol. V (1): 1 – 80. Gupta, S. P. 1959. Nematode parasites of vertebrates of East Pakistan III. Camallanidae from fishes, amphibian, reptiles. Canada J. Zool., Ottawa. 37: 771 – 779. Gupta, S. P. 1961. Caryophyllaeids from freshwater fishes of India. Proc. Helminth. Soc. Wash. 28 (1): 38 – 50. Gupta, P. C. 1983. Bifurcohaptor hemlatae n. sp. from a fresh water fish Rita rita from Kanpur. Ind. J. Parasitol. 7(2): 233 – 235. Gupta, S. P. and Verma, S. L. 1976. On some trematode parasites of freshwater fishes. Ribista-di-parasitologia. XXXVII (2-3): 171 – 182. Gupta, V. and Parmar, S. 1982. On a new cestode, Gangesia indica from a freshwater fish, W. attu from Lucknow, U. P, India. Indian Jour. of Helminthology. 34: 1, 44 – 49. Gupta, S. P. and Sharma, R. K. 1982. On some monogenetic trematodes of fishes. Among them Mizellus inglisi from W. attu is described in the river Gomati at Lucknow, India. Indian Jour. of Helminthology. 34: 2, 85 – 105. Gupta, A. K., Gaur, A. S. and Agarwal, S. M. 1983. Comparative studies on non-specific phosphomonoesterases, glycogen and pyrunic acid in I. hypselobagri from the air bladder and body cavity of W. attu from Raipur, M.P, India. Japanese Jour. of Parasitology. 32: 4, 357 – 361.

224

Gupta, V. and Singh, S. R. 1983. On a new species Pseudocaryophyllaeus ritai sp. nov. from the intestine of a fresh water fish Rita rita from river Gomati at Lucknow, U.P. Ind. J. Helminthol. 35 (1): 11 – 14. Gupta, P. G. and Govind, H. 1985. Three species of trematode parasites of the genus Haplorchoides from fresh water fishes of Kanpur, India. Ind. J. Parasitol. 9 (1): 35 – 39. Gupta, A. K. and Agarwal, S. M. 1986. Biochemical investigations on I. hypselobagri from swim bladder and body cavities of W. attu and C. punctatus from Raipur, India. Indian J. Parasitology. 10 (1): 47 – 51. Gupta, V. and Jaiswal, R. K. 1986. On some nematode parasites of vertebrates. Paracucullanellus thapari from intestine of W. attu from lucknow, U.P, India. Indian Jour. of Helminthology. 38: 1, 55 – 73. Gupta, P. C. and Masoodi, B. A. 1990. Two new and known spirurid nematodes from fresh water fishes at Kanpur. Ind. J. Helminthol. 42 (1): 31 – 36. Gupta, V. and Naiyer, N. 1990. On a new nematode Procamallanus guptai sp. nov. from intestine of a fresh water fish Heteropneustes fossilis from Lucknow. Ind. J. Helm. 42 (1): 67 – 71. Guziur, J. 1976. The feeding of two year old carp (Cyprinus carpio) in a vendace Lake Klawoj. Ekologia Polska. 24 (2): 211 – 235. Hafizuddin, A. K. M. and Khan, H. R. 1975. On new species of genus Genarchopsi. Bangladesh J. Zool. 1: 107 – 110. Hafizuddin, A. K. M. and Shahabuddin, M. 1996. Parasitic monogeneans from freshwater fishes of Commilla, Bangladesh. Chittagong Univ Stud Sci. 20: 113 – 126. Harrison, A., Gault, N. and Dick. J. 2006. Seasonal and vertical patterns of egg-laying by the freshwater fish louse Argulus foliaceus. Diseases of Aquatic Organisms, 68: 167 – 173. Haq, M. F. 1977. Determination of sexes in catfish of Bangladesh and Pakistan coasts. Bangladesh J. Zool. 5 (1): 33 – 40. Haque, A. 1975. Chemical constituent and preservation of fish. J. BCSIR (Dac). 10: 69 – 75. Hine, P. M. and Kennedy, C. R. 1974 a. Observation on the distribution, specificity and pathogenicity of the acanthocephalan Pomphorhynchus laevis. J. Fish Biol. 6: 521 – 535. 225

Hine, P. M. and Kennedy, C. R. 1974 b. The population biology of the acanthocephalan Pomphorhynchus laevis in Rive Avon. Jour. Fish Biol. 6: 665 – 679. Hine, P. M. 1980 a. Distribution of helminthes in the digestive tracts of New Zealand freshwater eels. I. Distribution of digeneans. N. Z. Jour. of Marine and Freshwater Research. 14 (4): 329 – 338. Hine, P. M.1980 b. Distribution of the helminthes in the digestive tracts of New Zealand freshwater eels. II. Distribution of nematodes. N.Z. Jour. of Marine and Freshwater Research. 14 (4): 339 – 347. Hiware, C. J. 1999: Population dynamics of the caryophyllaied cestode parasitizing fresh water air breathing predatory fish Clarias bataracus. Revista Di. Parasitologia. XIX (LXIII): 1. Hoffman, G. 1967. Parasites of North American freshwater fishes. Univ. of California press, Berkeley and Los Angeles. 486 pp. Hoffman, G. L. 1968. "Parasites of north American freshwater fishes". Comstock Publishing Associates, Itthaca and London. 539 pp. Hogan, C. M. 2010. Abiotic factor. Encyclopedia of earth. Eds. Emily Monosson and C. Cleveland. Natinal Council for Science and the Environment, Washington DC. Holmes, C. J. 1973. Site selection by parasitic helminths: Interspecific interactions, site segregation and their importance to the development of helminth communities. Can. J. Zool. 51: 333 – 347. Holmes, J. C., Hobbs, R. P. and Leong, T. S. 1977. Populations in perspective: community organization and regulation of parasite populations. In Regulation of Parasite Populations. (G. W. Esch, ed.). Academic Press, New York. 209 – 245 pp. Hossain, M. A. and Islam, M. S. 1983. Sexual dimorphism and sex ratio of Clupisoma atherinoides. Univ. J. Zool. Rajshahi Univ. 2: 71 – 72. Hossain, M., Islam, A. T. M. A. and Saha, S. K. 1987. Floods in Bangladesh-an analysis of their nature and causes. In: Floods in Bangladesh Recurrent disaster and people‟s survival. Universities Research Centre, Dhaka, Bangladesh, 1 – 21 pp. Hossain, M. A. and Barua, G. 1991. Diseases of cultured fish and their control. In "Improved Fish Culture Management Practices" (M. V. Gupta Ed.), Trainer's Training Manual for Fisheries Extension Officers. Fisheries Research Institute, Mymensingh. 175 – 191 pp.

226

Hossain, M. A. and Khan, M. H. 1992. Prevalence of ecto-parasites of carps in Bangladesh nurseries. In Third Asian Fisheries Forum, October 26-30, 1992, Singapore Abstracts. Asian Fisheries Society. 51 pp. Hossain, R. 1997. Morphology and histology of the digestive system of two catfish Clarias batrachus and Clarias gariepinus. M. Sc. Thesis, Department of Zoology, University of Dhaka. 85 pp. Hossain, M. M., Chandra, K. J. and Mohanta, S. K. 2000. Monogenetic trematodes from Puntius stigma of Mymensingh, Bangladesh. Riv Di Parassit. 61: 217 – 224. Humason, G. L.1979. Animal tissue techniques. 4th ed. W. H. Freemann and Company, San Francisco. 641 pp. Hunt, B. P. and Carbine, N. F. 1951. Food of young pike and associated fishes in Peterson‟s Ditches. Houghton Lake. Michigan. Trans. Am. Fish. Soc. 80: 67 – 73. Hunter, G. W. 1928. Contributions to the life history of Proteocephalus ambloplitis. J. Parasit. 14: 229 – 242. Hunter, G. W. III. 1930. Studies on the caryophyllaeidae of North American. III. Biol. Monog. 11: 186 pp. Hunter, G. W. III. and Hunter, W. S. 1942. Studies on host-parasite reactions. The integumentary type of strigeid cyst. Trans. Am. Micros. Soc. 61 (2): 134 – 140. Hutchings, J. A. and Baum, J. K. 2005. Measuring marine fish biodiversity: temporal changes in abundance, life history and demography. Philos Trans R Soc Lond B. 360: 315 – 338. Hynes, H. B. N.1950. The food of freshwater stickleback with a review of the methods used in studies of fishes. J. Anim. Ecol. 19: 41 – 57. Hyslop, E. J. 1980. Stomach contents analysis- a review of methods and their application. J. Fish. Biol. 17: 411 – 429. ICES (International Council for the Exploration of the Sea) 2006. In ICES report on ocean climate 2005, eds Hughes SL, Holliday NP (Intl Council for the Exploration of the Sea, Copenhagen, ICES Cooperative Research Report No. 280. IPCC (Intergovernmental Panel on Climate Change) 2007. Synthesis report. Contribution of working groups I, II and III to the fourth assessment report of the intergovernmental panel on climate change. Pachauri, R. K., Reisinger, A. (eds). Intergovernmental Panel on Climate Change, Geneva, Switzerland.

227

IPCC (Intergovernmental Panel on Climate Change) 2007. Assessment of adaptation practices, options, constraints and capacity. In: contribution of working Group II to the fourth assessment report of the intergovernmental panel on climate change. M.L. Pary, O. F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson, eds. Cambridge, Cambridge University Press. 976 pp. Islam, M. A. 1970. Studies on some endoparasites of common silurid fishes of Sunamganj. M.Sc. Thesis. DU. Islam, M. R., Sultana, N., Hossain, M. B. and Mondal, S. 2012. Estimation of fecundity and gonado somatic index (GSI) of gangetic whiting, Sillaginopsis panijus from the meghna river estuary, Bangladesh. J. World Applied Sci., 17: 1253 – 1260. Islam, M. S., Khanum, H., Sultana, A., Zaman, R. F. and Alam, S. 2015. Histopathological studies on epizootic ulcerative syndrome in some fishes from Demra, Dhaka. Bangladesh J. Zool. 43 (1): 121 – 130. Jafri, A. K. 1968 a. Seasonal changes in the biochemical composition of the common carp, Cirrhina mrigala. Broteria. 37: 29 – 44. Jafri, A.K. 1968 b. Seasonal changes in the biochemical composition of the catfish Mystus seenghala (SYKES). Broteria. 37: 45 – 58. Jafri, A. K. and Khawaja, D. K. (miss). 1968. Seasonal changes in the biochemical composition of the freshwater murrel, Ophiocepfalus punctatus. Hydrobiologia. 32: 1 – 2, 206 – 218. Jafri, A. K. 1969. Seasonal changes in the biochemical composition of freshwater catfish, W. attu. Hydrobiologia. 33: 497 – 506. Jahan, S. 1971. Studies on the histology and histochemistry of I. hypselobagri. M.Sc. Thesis, Dept. of Zool. Univ. of Dhaka. 112 pp. Jain, P. S., Pandey, K. C. and Pandey, A. K. 1976. Some histopathological observations on the stomach wall of Heteropneustes fossilis infected with a cestode. Agra. Univ. Jour. Of Res. Sci. 25 (3): 1 – 4. Jiménez-García, M. I. and Vidal-Martínez, V. M., 2005. Temporal variation in the infection dynamics and maturation cycle of Oligogonotylus manteri in the cichlid fish Cichlasona urophthalmus from Yucatan, Mexico. J. Parasitol. 91: 1008 – 1014. Jobling, M. 1994. Fish bioenergetics. Fish and Fisheries Series 13. Chapman and Hall, London. 309 pp. 228

Johnstone, J. 1918. The value of herrings as a food. Nature. 102: 6 – 7. Kabata, Z. 1985. Parasites and diseases of fish cultured in the Tropics. Taylor and Francis Ltd. 318 pp. Kader, M. A., Bhuiyan, A. L. and Manzur-I-Khuda, M. M. 1988. Food and feeding habits of Gobioides rubicundus and some feeding experiments on it. Indian J Fish. 35 (4): 312 – 316. Kakaji, V. L. 1968. Studies on helminth parasites of Indian fishes. Part I. Two trematode parasites of freshwater fishes from U.P. Indian Jour. of Helminthology. Vol. XX, 2: 136 – 144. Kamal, D., Khan, A. N., Rahman, M. A. and Ahamed, F. 2007. Biochemical composition of some small indigenous fresh water fishes from the river Mouri, Khulna, Bangladesh. Pak. J. Biol. Sci. 10 (9): 1559 – 1561. Kamaluddin, A., Malek, M. A. and Sanaullah, M. 1977. Deshio khaddeer pustiman. Ins. Nutr.Fd.Sci.DhakaUniversity. Karim, M. 1974. Bangladesh fisheries resources and development. Studies in Bangladesh Geography. Bangladesh National Geographical Association. An article. 1 – 16 pp. Karekar, P. S. and Bal, D. V. 1958. The food and feeding habits of Polynemous indicus Indian. J. Fish. 5: 77 – 94. Kennedy, C. R. and Walker, P. J. 1969. Evidence for an immune response by dace Leuciscus leuciscus to infections by the cestode Caryophylaeus laticeps. J. of Parasitology. 55: 579 – 582. Kannedy, C. R. 1977. The regulation of fish parasite population. In Regulation of parasite populations (G. W. Esch, ed.). Academic Press, New York. 63 – 109 pp. Kennedy, C. R. 1978. Ecological aspects of parasitology. North Holland Publishing Company. Amsterdam, Oxford. Kennedy, C. R. and Li, S. F. 1974. The distribution and pathogenecity of larvae of Eustrongylid in brown trout Salmo trutta in Fernworthy Reservoir, Devon. J. Fish. Biol. 8: 299 – 302. Khan and Yaseen 1969. Helminth parasites of fishes from East Pakistan, Nematodes. Bull. Dept. Zool. Univ. Punjab (M.S.), 1 – 33 pp. Khan, A. 1985. Phyllodistomum ritai, new species from a fresh water fish of kalri lake, Sind, Pakistan. Proceeding of Parasitology. 1: 1 – 5. Khan, R. A. and Thulin, J. 1991. Influence of pollution on parasites of aquatic animals. Adv Parasit 30: 201 – 239. 229

Khanum, H. A., Chowdhury, A., Latifa, G. B. and Nahar, N. 1989. Observation on helminth infection in relation to seasons and body lengths of Xenentedon cancila. Jour. Asiatic Soc. Bang. XV (1): 37 – 42. Khanum, H. A., Sufi, G. B. and Nahar, N. 1990. Incidence of helminth parasites in Xenentodon cancila in relation to food items. The Bangladesh J. of Sci. Res. 8 (2): 173 – 180. Khanum, H. A. and Begum, N. 1992. Size frequency of H. fossilis and its correlations of sizes with the rate of helminth infections. Bangladesh J. Zool. 20 (2): 305 – 314. Khanum, H. A., Zaman, Z. and Begum, N. 1992 a. Metazoan parasites of Heteropneustes fossilis. Bangladesh J. Zool. 20 (1): 103 – 112. Khanum, H., Zaman, Z. and Shahnaz. 1992 b. Metazoan infection in Glossogobius guiris in Bangladesh. Presented at Third Asian Fisheries Forum, Asian Fisheries Society, Singapore, From 26 to 30 October, 1992. Khanum, H. 1994. Endoparasitic helminth infestation in Ompok bimaculatus and Ompok pabda in relation to some of their biological, pathological and biochemical aspects. Ph. D Thesis. Dept. of Zoology, Univ. of Dhaka. 323 pp. Khanum, H., Ahmed, A. T. A. and Zaman, Z. 1996. Endoparasite community of two species of genus Ompak. J Bengal Nat His Soc N S. 15: 32 – 36. Khanum, H. A. and Parveen, S. 1997. Organal distribution and seasonal prevalence of endoparasites in Macrognathus aculeatus and Mastacembelus armatus. Bangladesh J. Zool. 25 (1): 15 – 21. Khanum, H. A and Zaman, R. F. 2002 a. Parasitic infestation of the fish Wallago attu. J. Asiat. Soc. Bangladesh, Sci. 28 (1): 129 – 132. Khanum, H. A and Farhana, R. 2002 b. Histopathological effects of a trematode Isoparorchis hypselobagri in Wallago attu. Bangladesh J. Zool. 30 (1): 65 – 69. Khanum, H. A., Khan, H. O. R. and Farhana, R. 2006. Infestation of ectoparasites in Gudusia chapra. Univ. J. Zool. Rajshahi Univ. 25: 23 – 25. Khanum, H., Ferdous, J. and Farhana, R. 2008 a. Community of helminth parasites in Rita rita in accordance to some its biological aspects. Rajshahi University J. of Zool. 36 (1): 56 – 62. Khanum, H., Nahar, S., Ferdous, Z., Uddin, H. M. and Kamrujjaman, M. 2008 b. Endohelminth infestation in Channa punctatus. Bangladesh J. Life. Sci. 20 (2): 17 – 25. 230

Khanum, H. and Yesmin, S. 2010. On the studies of parasites infestation in Clarias batrachus and Clarias gariepinus. 22nd National Congress of Parasitology, Dept. of Zoology, University of Kalyani, Kalyani, W.B. Khanum, H., Begum, S. and Begum, A. 2011. Seasonal prevalence, intensity and organal distribution of helminth parasites in Macrognathus aculeatus. Dhaka Univ. J. Biol. Sci. 20 (2): 117 – 122. Khusi, K., Khatun, A. and D'Silva, J. 1993. Cestode parasites from elamobrach fishes in the Bay of Bengal. In Annual Conference and General Meeting, 1992, Zoological Society of Bangladesh. Institute of Food and Radiation Biology, 12 pp. Atomic Energy Research Establishment, Savar, Dhaka. Klimpel, S., Seehagen, A., Palm, H. W. and Rosenthal, H. 2001. Deep-water metazoan fish parasites of the world. Logos Verlag, Berlin. Klimpel, S., Busch, M. W., Kellermanns, E., Kleinertz, S. and Palm, H. W. 2009. Metazoan deep-sea fish parasites. Acta Biologica Benrodis, Suppl. 11, Verlag Natur and Wissenschaft, Solingen. Kulasiri, C. and Fernando, C. H.1956. Camallanidae parasitic in some Ceylon fish. Parasitology. 46: 420 – 424. Lageer, K. F. 1949. Studies in fresh water fishes biology. Ann. Abar. Michigan. 119 pp. Lagler, K. F. 1956. Fresh water fishery biology, 2nd edi. Dubuque, lowa; Wm, C. Brown Publ. Com., 421 pp. Lagler, K. F.1962. Freshwater fishery biology. 2nd edi. Dubuque, lowa, Wm. C. Brown. 421 pp. Landsberg, J. H., Blakesley, B. A., Reese, R. O., McRae, G. and Forstchen, P. R. 1998. Parasites of fish as indicators of environmental stress. Env Monit Assess. 51: 211 – 232. Lawrence J. L. (1970): Effect of season, host age on endohelminths of Castostomus commersoni. J. Parasitology. 56 (3): 567 – 571. Lilabati, H. and Viswanath, W. 1996. Nutritional quality of freshwater catfish (Wallago attu) available in India. Food Chem. 57: 197 – 199. Linacre, E. 1992. Climate data and resources: a reference and guide. Routledge, London and New York, 260 – 261 pp. Love, R. M. 1980. The chemical biology of fishes. Academic Press, London. Lyngdoh, R. D. and Tandon, V. 1998. Putative neurosecretory cells in the monozoic cestode, Lytocestus indicus. Acta Parasitologica, 43 (2): 216 – 220. 231

Mackiewicz, J. S. 1972. Parasitological review: Caryophyllidea (Cestoda). A review. Experimental parasitology. 31: 417 – 512. Mackiewicz, J. S. 1972. Relationship of pathology to scolex morphology among caryophyllid cestodes. Z. Parasitenk. 39: 233 – 246. Mackiewicz, J. S., Cosgrov, G. E. and Gude, W. D. 1972. Relationship of pathology to scolex morphology among caryophyllid cestodes. Z. Parasitenk. 39: 233 – 246. Mackiewicz, J. S. 1982. Caryophyllidea (Cestoidea) Perspectives. Parasitology. 84: 397 – 417. Mackenzie, K. and Gibson, D. J. 1970. Ecological studies of some parasites of plaice Pleuronectes platessa and flounder Platichthys flesus. Sym. Br. Soc. Parasit. 8: 1 – 42. MacKenzie, K., Williams, H. H., Williams, B., McVicar, A. H. and Siddall, R. I. 1995. Parasites as indicators of water quality and the potential use of helminth transmission in marine pollution studies. Adv Parasitol. 35: 86 – 245. Macnab, V. and Barber, I. 2011. Some (worms) like it hot: fish parasites grow faster in warmer water and alter host thermal preferences. Global Change Biology. Mahajan, C. L., Agarwal, N. K., John, M. J. and Katta, V. P. 1978. Parasitization of I. hypselobagri in C. punctatus Blovh. Curr. Sci. 47 (21): 835 – 836. Mahfuj, M. S. E., Hossain, M. B. and Minar, M. H. 2012. Biochemical composition of an endangered fish, Labeo bata from Bangladesh waters. American Journal of Food Technology. 7: 633 – 641. Mandal, H. P. 1995. Studies on helminth parasite of lizardfish, Saurida tumbil. M. Sc. thesis submitted to the Department of Fisheries, Biology and Limnology; BAU, Mymensingh. 75 pp. Mannan, A. 1977. Nutritional aspects of marine fishes and fisheries products. Margolis, L. and Arthur, J. R. 1979. Synopsis of the parasites of fishes of Canada. Bull Fish Res Bd Can. 199: 1 – 269. Margolis, L., Esch, G. W., Holmes, J. C., Kruis, A. M. and Schad, G. A. 1982. The use of ecological terms in Parasitology (Report of an adhoc committee of the American Soc. of Parasitologists). J. Parasitol. 68 (1): 131 – 133. Markov, G. S. 1946. Modes of feeding of parasites priroda, XII. (Quoted from Dogiel, 1961).

232

Martin, L. B., Pless, M., Svoboda, J. and Wikelski, M. 2004. Immune activity in temperate and tropical house sparrows: a common-garden experiment. Ecology. 85: 2323 – 2331. Mashego, S. N. and Saayman, J. E. 1989. Digenetic trematodes and cestodes of Clarias gariepinus in Lebowa, South Africa, with taxonomic notes. South African J. Wildlife-Research. 19 (1): 17 – 20. Maurya, A. K., Agarwal, G. P. and Singh, S. P. N. 1989. On a new species Masenia chauhani sp. nov. from the intestine of a fresh water fish Rita rita from Varanasi (U.P.) Ind. J. Helminthol. 41 (2): 149 – 151. McDonald, T. E. and Margolis, L. 1995. Synopsis of the parasites of fishes of Canada: Supplement (1978 – 1993). Can Spec Publ Fish Aquat Sci. 122: 1 – 265. Mellanby, H. 1963. Animal life in freshwater (6th ed.). Methuen and Co.Ltd. London. 300 pp. M€oller, H. 1987. Pollution and parasitism in the aquatic environment. Int J Parasitol. 17: 353 – 361. Minar, M. H., Adhikary, R. K., Begum, M., Islam, M. R. and Akter, T. 2012. Proximate composition of Hilsa (Tenualosa Ilisha) in laboratory condition. Bangla. J. Progres. Sci. Technol. Vol. 10. Mitchell, A. J., Smith, C. E. and Hoffman, G. L. 1982. Pathogenecity and histopathology of an unusually intense infection of white grubs (Posthodiplostomum m. minimum) in the fathead minnow (Pimephales promelas). J. of Wildlife Diseases 18 (1): 51 – 57. Moffett, J. W. and Hunt, B. P. 1943. Winter feeding habits of blue-gills, Lepomis macrochiri and yellow pertch Perca flavescens, in Cader lake, Washtenaw Country. Michigan. Trans. Amer. Fish. Soc. 73 pp. Mohanta, S. K. and Chandra, K. J. 2000. Monogenean infestation in Thai Silver barb (Barbodes gonionotus) and their adaptations in Bangladesh waters. Bangladesh J Fish Res. 3: 147 – 155. Mohanta, S. K., Chandra, K. J. and Hossain, M. M. 2000. Dactylogyrid monogeneans from two Puntius species of Mymensingh, Bangladesh. Riv Di Parassitol 61: 209 – 216.

233

Mookherjee, H. K., Gupta, S. N. and Chaudhury, R. P. K. 1946. Food and its percentage composition of the common adult fishes of Bengal. Sci. and Cult. 12: 247 – 249. Mookherjee, H. K. and Mazumder, S. R. 1950. Some aspects of the life history of Clarias batrachus. Proc. Zool. Soc. Bengal. 3 (3): 71 – 79. Moravec, F. 1998. Nematode of freshwater fishes of the Neotropical Region. Academia Praha. 4: 64 pp. Murshed, S. B., Islam, A. K. M. S. and Khan, M. S. A. 2011. Impact of climate change on rainfall intensity in Bangladesh. 3rd International Conference on Water and Flood Management (ICWFM). Mustafa, G. and Ahmed, A. T. A. 1979. Food of Notopterus notopterus. Bangladesh J. Zool. 7 (1): 7 – 14. Mustafa, G. K., Islam, R. and Ali, S. 1981. Seasonal patterns of feeding of the fresh water fish, Colisa fasciatus. Bangladesh J. Zool. 9 (1): 49 – 50. Nahar, N. 1988. Prevalence and intensity of helminth parasites of X. cancila in relation to some of its biological aspect. M.Sc. Thesis, Dept. of Zool. Univ. Dhaka. 1 – 129 pp. Nahar, S. 1993. Comparative study on incidence of endoparasites in relation to some biological aspects of Channa striatus and Channa marulius from Dhaka, Bangladesh. M. Sc Thesis, Dept. of Zool., Univ. of Dhaka. Nahida, K. 1993. Studies on the helminth parasites and histopathology of infested organs in Nandus nandus. M.Sc thesis, Eden Univ. College, Dhaka. 178 pp. Naser, M. N. and Mustafa, T. 2006. Histological and histomorphometric aspects of the digestive system of the taki fish, Channa punctatus. Bangladesh J. Zool. 34 (2): 205 – 212. Naser, M. N., Chowdhury, G. W., Begum, M. M. and Haque, W. 2007. Proximate composition of prawn, Macrobrachium rosenbergii and shrimp, Penaeus monodon.DhakaUniv.J.Biol.Sci.,16:61–66. Nikolosky, G. V. 1963. The ecology of fish. Academic Press. London and New York. 352 pp. Nilson, 1946. The value of fish and shellfish, food Research. 30: 177 pp. Nittleton, A. 1985. Nutrients and substances in fresh seafood. In Seafood nutrition facts, issues and marketing of nutrition of fish and shellfish. Van Nostrand Reinhold, New York. 30 – 64 pp. 234

Oktener, A., Ali, A., Gustinelli, A. and Fioravanti, M. 2006. New host records for fish louse Argulus foliaceus in Turkey. Ittiopatologia, 3: 161 – 167. Oktener, A., Trilles, J. and Leonardos, I. 2007. Five ectoparasites from Turkish fish. Turkiye Parazitologi Dergisi, 31: 154 – 157. Olsen, O. W. 1974. Animal parasites, their life cycles and ecology. 3rd edi. Univ. Park Press, Baltimore, London, Tokyo. 562 pp. Ozaki, Y. 1926. On two new genera of frog trematodes, Cryprtotrema and Macrolecithus and a new species of Pleurogenes. Jour. Fac. Sci. Imp. Univ. Tokyo. Sect. N. Zool. 1 (1): 33 – 44. Palm, H. W. and Dobberstein, R. C. 1999. Occurrence of trichodinid ciliates in the Kiel Fjord, Baltic Sea, and its possible use as a biological indicator. Parasitol Res. 85: 726 – 732. Palm, H. W. and R€uckert, S. 2009. A new approach to visualize ecosystem health by using parasites. Parasitol Res. 105: 539 – 553. Palm, H. W. Aquakultur und Sea-Ranching, Progress in Parasitology, Parasitology Research Monographs 2, DOI 10.1007/978-3-642-21396-0_12, # Springer-Verlag Berlin Heidelberg 2011, Chapter - 12 (Fish Parasites as Biological Indicators in a Changing World: Can We Monitor Environmental Impact and Climate Change?) Parveen, R. and Silva, J. D. 2006. Helminth parasites in Anabas testudineus. Bang. J. Zool. 34(1): 35 – 40. Parveen, R., Silva, J. D., Khanum, H. and Zaman, Z. 2006. Helminth parasites in Anabas testudineus. Bang. J. Zool. 34 (1): 35 – 40. Parveen, R. and Silva, J. D. 2007. Helminth parasites in Nandus nandus. Bang. J. Life. Sci. 19 (1): 101 – 106. Pasternak, A., Mikheev, V. and Valtonen, E. 2000. Life history characteristics of Argulus foliaceus populations in Central Finland. Annales Zoologici Fennici, 37: 25 – 35. Pasternak, A., Mikheev, V. and Valtonen, E. 2004. Growth and development of Argulus coregoni on salmonid and cyprinid hosts. Diseases of Aquatic Organisms, 58: 203 – 207. Pearson, D. 1962. General methods, fat in the chemical analysis of foods. J. and A. Churchill Ltd. London. 26 – 28 pp.

235

Pennycuick, L. 1971 a. Frequency distribution of parasites in a population of three- spined stickleback, Gasterosteus aculeatus of different sex, age and size with the particular reference to the negative binomial. Parasitology. 63: 389 – 406. Pennycuick, L. 1971 b. Seasonal variations in parasitic infection in a population of three-spined stickleback, Gasterosteus aculeatus. Parasitology. 63: 373 – 388. Pillay, T. V. R. 1952. A critique of methods of study of the food of fishes. J. Zool. Soc. Indian. 4 (2): 185 – 200. Poulin, R. and Morand, S. 2004. Parasite biodiversity. Smithsonian Institution. 216 pp. Promas, C. and Daengsvang, S. 1937. Feeding experiments on cats with G. spinigerum larvae obtained from the 2nd intermediate host. J. Parasitology. 23: 115 – 116. Rafiuddin, M., Uyeda, H. and Islam, M. N. 2009. Simulation of characteristics of precipitation systems developed in Bangladesh during pre-monsoon and monsoon (Proceedings of the 2nd International Conference on Water and Flood Management held at Dhaka, Bangladesh, March 2009), Institute of Water and Flood Management, BUET, Dhaka, Bangladesh Publication. 1: 61 – 68. Rahman, A. K. 1989. Freshwater fishes of Bangladesh. Zool. 2 (1): 1 – 12. Rahman, A. K. M. 1974. An aid to the identifications of the Mystid catfishes of Bangladesh. Bang. J. Zool. 2 (1): 1 – 12. Rahman, A. K. M. 1968. A note on Argulus spp. which cause mortality in carps in the experimental cistern of freshwater research station, Chandpur, East Pakistan. Pak J. Sci. Ind. Res. 11 (1). Rahman, A. K. A. 1971. On the occurrence of a larval cestode Gymnorchynchus spp. in the coelom of P. pama from the river Padma and Meghna. Rahman, A. K. A. and Ali, M. Y. 1966. The incidence of nematodes P. heteropneustes in the stomach of H. fossilis. Pak. J. Sci. India. Res. 11 (1). Rajeswari, J. S. and Kulkarni, T. 1983. On a new species Bychowskyella singhi from the gills of freshwater fish, W. attu from Hyderabad, A. P., India. Proceedings of the Indian Academy of Parasitology. 4: ½, 49 – 53. Rao, N., Kemeswari, M. and Rao, G. R. H. 1979. An yet unidentified host of I. hypselobagri. Curr. Sci. 48 (7): 320 pp. Rao, P. S. and Simha, S. S. 1983. Phosphatase activity in I. hypselobagri of W. attu in Hyderabad, A. P., India. Proceedings of the Indian Academy of Parasitology. 4 : ½, 33 – 35. 236

Rashid, M. M., Haque, A. K. M. and Chandra, K. J. 1983. Records of some metazoan parasites of Clarias batrachus from Mymensingh. Bangladesh J Fish. 6: 37 – 42. Rashid, M. M., Haque, A. K. M. and Chandra, K. J. 1984. Effect of season, sex and size of Clarias batrachus on the population of Orientocreadium batrachoides in Mymensingh, Bangladesh. Bangladesh J Fish. 7: 21 – 25. Rashid, M. M., Haque, A. K. M. and Chowdhury, M. B. R. 1985. Population dynamics of caryophyllid cestodes parasitizing Clarias batrachus. Bangladesh J Agril Sci. 12: 169 – 174. Rehana, R. and Bilques, F. M. 1972. Neocamallanus ophiocephali from the fishes O. striatus and W. attu of Katri lake, Sind area, West Pak. Pak. Agri. Res. Council. 72, 92 – 96 pp. Rehana, 1974. P. wallagus from the fish W. attu of Sind. Sind. Univ. Res. J. (Sciser) 7(½): 13 – 16. Rehana, 1979. 3 nematode species of genus Procamallanus including 2 new species from the fishes of Kalri lake, Sind. Pakistan. Pak. J. Zool. 11(2): 281 – 293. Reynolds, J. D., Webb, T. J. and Hawkins, L. A. 2005. Can J Fish Aquat Sci. 62: 854 – 862. Ribelin, W. E. and Migaki, G. 1975. The pathology of fishes. The Uni. of Wisconsin press. Mac Wisconsin. 1004 pp. Roberts, R. J ., Machintosh, D. J., Tonguthai, K., Boonyaratpalin, S., Nuansri, T., Phillips, M. J. and Millar, S. D. 1986. Field and laboratory investigation into ulcerative fish diseases in the Asia Pacific region. Technical report of FAO project TCP/RAS/4508. Bankok, Thailand. 213 pp. Roberts, R. J., Willoughby, L. G., Chinabut, S. and Tonguthai, K. 1993. Mycotic aspects of epizootic ulcerative syndrome (EUS) of asian fishes. J. Fish. Dis. 16: 169 – 183. Rohde, K. 2002. Ecology and biogeography of marine parasites. Adv Mar Biol. 43: 1 – 86. Roopma, G., Gupta, V., Meenakshi, K. and Sweta, G. 2013. Quality changes in the muscles of Wallago attu during frozen storage (-12±2ºC) conditions. Res. J. Animal, Veterinary and Fishery Sci. 1 (5): 16 – 20. Rubbi, S. F., Rahman, M. M., Khan, A. R., Jahan, S. S. and Begum, M. 1987. Studied on the proximate composition and quality of some commercial species of fresh water fish. Bangladesh J. Sci. Res. 5 (1): 1 – 20. 237

Saha, P. K., Chandra. K. J. and Ghosh, P. K. 2003. Monogenean parasites of certain small indigenous fish species of Bangladesh. Riv. Di Parassit. 64: 203 – 215. Sanaullah, M. and Ahmed, A. T. A. 1978. Observations on some aspects of association in the parasite infections in the catfishes Heteropneustes fossilis and Clarias batrachus of Bangladesh. Bangladesh J. Fish. 1 (2): 73 – 84. Sanaullah, M. and Ahmed, A. T. A. 1980. Gill myxoboliasis of major carps in Bangladesh. J Fish Dis. 3: 349 – 354. Sanaullah, M., Hjeltnes, B. and Ahmed, A. T. A. 1997. Histopathological aspects of epizootic ulcerative syndrome (EUS) in wild fishes from Faridpur, Bangladesh. Bangladesh J. Zool. 25 (2): 183 – 193. Shahadev, X. V. and Simha, S. S. 1980. A new host record for I. hypselobagri. GEOBIOS. 7 (16): 272 – 273. Schmidt, G. D. 1970. Foundation of Parasitology. 5th edi. Wm. C. Brown. Company Publishers. 659 pp. Scott, J. S. 1975 a. Incidence of trematode parasites of American Plaice (Hippoglossoides platessoides) of the Scotian Shelf and Gulf of St. Lawrence in relation to fish length an food. Fisheries Res. Board Canada. 32 (4): 479 – 483. Scott, J. S. 1975 b. Geographic variation in incidence of trematode parasites of American Plaice (Hippoglossoides platessoides) in the northwest Atlantic. Fisheries Res. Board Canada. 32(4): 547 – 550. Shafi, M. and Quddus, M. M. A. 1982. Bangladesher Matshya Sampad (Fisheries of Bangladesh, in Bengali). Bangla Academy, Dhaka. 444 pp. Sharpe, D. M. T. and Hendry, A. P. 2009. Life history change in commercially exploited fish stocks: an analysis of trends across studies. Evol Appl 2: 260 – 275. Shotter, R. A. 1980. Aspects of the parasitology of the catfish Clarias anguillaris (L.) from a river and a lake at Zaria, Kaduna State, Nigeria. 123 pp. Siddiqui, A. and Nizami, A. 1978. Incidence of Isoparorchis hypselobagri in Wallago attu, with remarks on its life cycle. Acta Parasitologica Polonish. 25 (25): 223 – 227. Siddique, M. A. M., Mojumder P. and Zamal, H. 2012. Proximate composition of three commercially available marine dry fishes (Harpodon nehereus, Johnius dussumieri and Lepturacanthus savala). Am. J. Food Technol. 7: 429 – 436. Sindermann, C. J. 1970. Principal diseases of marine fish and shellfish. Academy Press, New York. 165 pp. 238

Singh, H. S. and Jain, A. 1988. On a new monogenetic trematode, Dagielius gussevi n. sp. from a fresh water fish R. rita. Uttar-pradesh J. Zool. 8 (1): 90 – 93. Singhvi, N. R., Bose, P. C., Subbaswamy, M. R., Basavanna, H. M., Vreddy, M. M. and Majumder, S. K. 1987. Chemistry and Sericulture Indian Silk, 26 (7): 24 – 25. Sinha, K. P. 1988. Procamallanus infection in the fish Clarias batrachus. Environment and ecology. 6 (4): 1035 – 1037. Siva, R. Y. and Rao, B. M. 1983. A note on the food of Mystus vittatus from the highly polluted Hussain Sagar Lake, Hyderabad. Dept. of Zoology, Babu Jagjivan Ram College. 484 – 487 pp. Smith, H. D. 1973. Observations on the cestode Eubothrium salvelini in juvenile Sockeye salmo (Oncorhynchus nerka) at Babine Lake, British Columbia. J. Fish. Res. Bd. Can. 30: 947 – 964. Snieszko, S. F. 1983. Diseases of fishes: Research and control. Fisheries. 8: 20 – 22. Soderberg, R. W. 1984. Comparative Histology of Rainbow trout and channel catfish grown in intensive static water aquaculture. Progressive fish culturists. 3: 195 – 199. Souidenne, D. 2011. Contribution à l‟étude de la copépodofaune des poissonstéléostéens du golfe de Hammamet. Mémoire de Mastère, F.S.T. 1 – 199 pp. Soulsby, E. J. L. 1968. Helminth, arthropods and protozoa of domestic animals. 6th edition. Lea and Febiger, Phildelphia. 824 pp. Southwell, T. 1913. Notes from the bengal fisheries laboratory. Indian museum. No. 1. Rec. Ind. Mus. 9, 79 – 103 pp. Southwell, T. 1913. On some indian cestoda. Pt. I. Rec. Ind. Mus. 9, 279 – 300 pp. Southwell, T. 1930. Cestoda. In the fauna of British India including ceyloneand Burmm Vols. I and II. London. Srivastava, H. D. 1936. New hemiurids from indian fishes. Pt. I. A. New parasite of the sub-family: prosarechinae. Proc. Nat. Acad. Sci. India. 6: 1974 – 1978. Srivastava, C. B. and Mukherjee, G. D. 1974. Studies on the incidence of infestation of I. hypselobagri metacercaria in two species of fishes of the genus Mystus. Jour. of Zool. Soc. India. 26 (1 and 2): 131 – 137. Srivastava, H. D. 1977. Isoparorchis hypselobagri, its hosts, distribution and relationships. In Excerta Parasitologica en memoria del Doctor Eduardo Caballero y Caballero. Mexico. Universidad National Autonoma de Mexico. 325 – 333 pp.

239

Stansby, M. E. 1954. Composition of certain species of freshwater fish. Food Res.19: 231 – 234. Steinauer, M. L. and Font, W. F., 2003. Seasonal dynamics of the helminths of bluegill (Lepomis macrochirus) in a subtropical region. J. Parasitol. 89: 324 – 328. Stromberg, P. C. 1973. The life history and population ecology of Camallanus oxycephalus in fishes of Western lake. Erie. Ph.D dissertation, Ohio State University (quoted from Stromberg and Crites, 1974) Sultana, Q., Rahim, K. A., Ahmed, A. T. A. and Rahman, M. 1992. Effect of helminth infestation and seasonal variation of the nutritional quality of C. batrachus. Dhaka, Univ. Stud. Part E, 7 (1): 1 – 6. Symasunder, P., Aruna, K. and Rao, P. S. 1984. Succinate dehydrogenase activity in the fish parasite I. hypselobagri. In Osmania Univ. Hyderabad, India. Proceeding of the Indian Academy of Parasitology. 5 (½): 39 – 41. Talwar, P. K. and Jhingran, A. G. 1991. Inland fishes of India and adjacent countries. Vol. II. Tang, H., Chen, L., Xiao, C. and Wu, T. 2009. Fatty acid profiles of muscle from large yellow Croaker (Pseudosciaena crocea) of different age. J. Zhejiang Univ. Sci. B. 10 (2): 154-158. Taylor, N., Sommerville, C. and Wootten, R. 2006. The epidemiology of Argulus spp. infections in still water trout fisheries. Journal of Fish Diseases, 29: 193 – 200. Tedla, S. and Feranndo, C. H. 1969. Observation on the seasonal change of the parasite fauna of Yellow perch (P. flavescens) from the Bay of Quinte, Lake Ontario. Jour. Fish. Res. Board of Canada. 26 (4): 833 – 843. Thomas, J. D. 1964. Studies on population of helminth digenetic trematode of vertebrates Part.I and II. Interscience publishers Ltd. London. Turner, W. C., Versfeld, W. D., Kilian, J. W. and Getz, W. M. 2012. Synergistic effects of seasonal rainfall, parasites and demography on fluctuations in springbok body condition. J Anim Ecol. 81 (1): 58 – 69. Uddin, M., Dewan, M. L., Hossain, M. I. and Huq, M. M. 1980. Occurrence of Diphyllobothrium latus larvae (plerocercoid) in loitya (Harpodon nehereus) fish. Bangladesh Vet J. 14: 33 – 35.

240

Uddin, A. M. K. 2009. Climate change and Bangladesh. Seminar on Impact of Climate Change in Bangladesh and Results from Recent Studies. Organized by Institute of Water Modeling. Ulmer, M. J. 1971. Site finding behavior in helminthes in intermediate and definitive hosts. Ini. A. M. Follis (Ed). Ecology and Physiology of parasites. Adam Hilger. Ltd. London. 123 – 129 pp. University of Leicester. 2011. "Global warming changes balance between parasite and host in fish." Science Daily. . Venkateshappa, T., Seenappa, D. and Manohar, L. 1988. New host records of fish louse, E. malnadensis from Karnataka, India. Curr. Sci. India. 57: 4, 210 pp. Venkateshappa, T., Seenappa, D. and Manohar, L. 1988. E. malnadensis, parasitic on W. attu. Univ. of Agricultural science. Bangalore, India. Mysore Jour. of Agri. Sci. 22: 3, 388 – 394. Venkateshappa, T., Seenappa, D. and Manohar, L. 1988. Incidence and intensity of E. malnadensis infestation on W. attu in Vanivilasa Sagar Reservoir, Karnataka. Mysore Jour. of Agri. Sci. 22: 4, 523 – 530. Verma, T. K. and Ahluwalia, S. S. 1980. An unusual record of I. hypselobagri, a trematode parasite of fishes from the bile duct of a pig. India veterinary Jour. 57: 688 – 689. Vidal-Martı ´nez, V. M., Pech, D., Sures, B., Purucker, S.T. and Poulin, R. 2010. Can parasites really reveal environmental impact? Trends Parasitol. 26: 44 – 51. Vinod Agarwal 1964. On some new trematodes from fresh water fishes of Lucknow. Indian Journal of Helminthology. XVI (2): 82 – 99. Wabuke, M. A. N. and Bunoti 1980. The prevalence and pathology of the cestode Polyonchobothrium clarias in the teleost, Clarias mossambicus. Jour. Fish Disease. 3: 223 – 230. Walker, P., Harris, J., Velde, G. V. and Bonga, S. 2007. Size matters: stickleback size and infection with Argulus foliaceus. Crustaceana, 80: 1397 – 1401. Wasimi, S. A. 2009. Climate change trends in Bangladesh (Proceedings of the 2nd International Conference on Water and Flood Management held at Dhaka, Bangladesh, March 2009), Institute of Water and Flood Management, BUET, Dhaka, Bangladesh Publication. 1: 203 – 210.

241

Weatherley, A. H. and Gill, H. S. 1987. The biology of fish growth. Academic Press. London. 1 – 443 pp. Wickins, J. F. and MacFarlance 1973. Some differences in the parasitic fauna of three samples of Plaice (Pleuronectes platessa) from the southern North Sea. J. Fish. Biol. 5: 9 – 19. Williams, H. H. 1960. Some observations on Parabothrium gadipollachi and Abothrium gadi including an account of the mode of attachment and variation in two species. Parasitology. 50: 303 – 322. Winifred, M. C. 1972. Statistics in small doses. Churchill Livingstone, Edinburgh and London. 216 pp. Woodland, W. N. F. 1935. Some more remarkable cestodes from amajon siluroid fish. Parasitology. 27: 207 – 225. Wootten, R. and Smith, J. W. 1975. Observation and experimental studies on the acquisition of Anasakis sp. larvae by trout in fresh water. Int. J. of Parasitology. 5: 373 – 378. Wootton, R. J. 1990. Ecology of teleost fishes. 1st Edn., Chapman and Hall, London, UK. ISBN-13: 9780412317200, 404 pp. World Fish Center. 2007. Fisheries and aquaculture can provide solutions to cope with climate change. Issues brief. World Fish Center, Penang, Malaysia. Yamaguti, S. 1958. Systema helminthum. The digenetic trematodes of vertebrates. Interscience Publishers, New York, London. Vol. I. Part I and II. 1575 pp. Yamaguti, S. 1959. Systema helminthum. The cestode of vertebrates. Vol. II. John Wiley and Sons. 860 pp. Yamaguti, S. 1961. Systema helminthum. Vol. V. The acanthocephala. John Wiley and Sons. 423 pp. Yamaguti, S. 1961. Systema helminthum. Vol. III. The nematodes of vertebrates. Interscience, Part I and II. Interscience Publishers, New York. 1261 pp. Yamak, S. S. 2000. Impact d‟unepisciculturesurl‟ Ichtyofaune et l‟Ichtyoparasitofaune d‟un environnement lagunaire. D.E.A. Faculté des Sciences de Tunis, Univ. Tunis. II: 1 – 206.

242

Yasmin, S., Rahim, K. A., Shekhar, H. U. and Ahmed, A. T. A. 1994. Identification, organal distribution, seasonal variation and correlation of prevalence and intensity of infestation of helminthes in Clarias batrachus. Dhaka University J. Biol. Sci. 3 (2): 107 – 117. Yeh, L. S. 1960. On a reconstruction of the genus Camallanus. J. Helminth. 34: 117 – 124. Yeomans, W. E., Chubb, J. C. and Sweeting, R. A. 1997. Use of protozoan communities for pollution monitoring. Parasitologia. 39: 201 – 212. Yesmin, S and Khanum, H. 2013. Histo-pathological affects due to helminth infestation in Clarias batrachus and Clarias gariepinus. 23rd National Congress of Parasitology Dept. of Zoology, Kalyani University, Kalyani, West Bengal. 309 – 315 pp. Zaman, Z. 1985. Parasite fauna of paddy field catfish (Clarias sp.) from Kedah and Perak, Peninsular Malaysia. Ph.D Thesis. Universiti Sains Malaysia. 224 pp. Zaman, Z. and Leong, T. S. and Khanum, H. A. 1986. Effects of lengths (=age) of Clarias on abunadance of parasites. Bangladesh J. Zool. 14: 171 – 177. Zaman, Z. and Seng, L. T. 1986. Histopathology of the intestine caused by a caryophyllid cestode, Djombangia penetrans in catfish Clarias batrachus and Clarias macrocephalus. Tropical Biomedicine. 3: 157 – 160. Zaman, Z. and Leong, T. S. 1987. Occurrence of the caryophyllid cestode Lytocestus parvulus in Clarias batrachus in a tropical environment, Kedah, Malaysia. Jour. Fish. 31: 591 – 596. Zaman, Z. and Leong, T. S. 1988. Occurrence of Procamallanus malaccensis in Clarias batrachus and Clarias macrocephalus from Kedah and Perak, Malaysia. Asian Fisheries Science. 2: 9 – 16. Zaman, Z. and Khanum, H. A. 1990. The lernaeid Copepod parasites Lernaea cyprinacea in C. batrachus. The Bangladesh J. of Scientific Research. 8 (2): 165 – 171. Zaman, R. F. and Khanum, H. 2013. Proximate analysis of Mystus aor and Mystus bleekeri in relation to parasitic infestation. 23rd National Congress of Parasitology. Dept. of Zoology, Kalyani University, Kalyani, West Bengal. 69 – 78 pp.

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Websites:

[www.fao.org/index_en.htm/FAO Fisheries & Aquaculture - National Aquaculture Legislation Overview - Bangladesh.htm]

[www.fisheries.gov.bd/fish production.htm.]

[http://www.wunderground.com/history/airport/OPSK/2013/7/6/DailyHistory.html]

[https://en.wikipedia.org/wiki/Humidity]

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Appendix

Ecto-parasites

Fig. Lernaea cyprinacea

Fig. Argulus foliaceus

245

Trematode parasites

Fig. Magnacetabulum trachuri Fig. Notoporus leiognathi

Fig. Saccacoelium obesum Fig. Sterrhurus musculus

246

Trematode parasites

Fig.Clinostomum piscidium Fig.Macrolecithus gotoi

Fig. Isoparorchis hypselobagri

247

Cestode parasite

Fig. Polyoncobothrium polypteri (anterior end)

Fig. Polyoncobothriumpolypteri (gravid segments)

248

Nematode parasites

Fig. Cosmoxynemoides aguirrei Fig. Contracaecum L3 larva

Fig. Ascaroid larva

249

Acanthocephalan parasites

Fig. Acanthocephalus aculeatus Fig. Corynosoma alaskense

Fig. Corynosoma strumosum Fig. Pallisentis umbellatus

250

Acanthocephalan parasites

Fig. Echinorhynchus kushiroense Fig. Echinorhynchus kushiroense (anterior end) (posterior end)

Fig. Pallisentis ophiocephali Fig.Pallisentis ophiocephali (anterior end) (posterior end)

251

Acanthocephalan parasite

Fig. Cavisoma magnum (anterior end)

Fig. Cavisoma magnum (posterior end)

252

Table (a): Monthly prevalence of Lernaea cyprinacea in R. rita (Jan’11 – Dec’12)

Male Female Month No. of fish No. of fish Prevalence No. of fish No. of fish Prevalence examined infected (%) examined infected (%) J 12 2 16.66 7 3 42.85 F 11 2 18.18 6 1 16.66 M 12 2 16.66 6 1 16.66 A 12 1 8.33 5 1 20 M 6 1 16.66 9 2 22.22 J 11 1 9.09 6 2 33.33 J 10 1 10 6 1 16.66 A 9 2 22.22 7 1 14.28 S 11 1 9.09 6 2 33.33 O 12 2 16.66 4 0 0 N 11 0 0 6 2 33.33 D 9 4 44.44 7 1 14.28 J 8 3 37.5 4 1 25 F 9 5 55.55 5 1 20 M 6 1 16.66 5 2 40 A 7 1 14.28 4 4 100 M 6 0 0 6 3 50 J 5 1 20 6 3 50 J 10 0 0 4 4 100 A 9 1 11.11 4 2 50 S 9 1 11.11 5 4 80 O 6 0 0 7 3 42.85 N 5 0 0 8 4 50 D 4 4 100 7 3 42.85

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Table (b): Monthly prevalence of Argulus foliaceus in W. attu (Jan’11 – Dec’12)

Male Female Month No. of fish No. of Prevalence No. of fish No. of Prevalence fish fish

examined infected (%) examined infected (%) J 5 1 20 6 0 0 F 5 0 0 5 0 0 M 3 1 33.33 8 1 12.5 A 5 0 0 5 1 20 M 3 1 33.33 7 0 0 J 5 1 20 6 0 0 J 3 1 33.33 7 1 14.3 A 5 1 20 5 1 20 S 3 3 100 8 1 12.5 O 4 0 0 5 0 0 N 5 2 40 5 2 40 D 3 2 66.66 8 1 12.5 J 5 1 20 6 4 66.66 F 3 1 33.33 6 2 33.33 M 5 1 20 5 3 60 A 5 1 20 6 3 50 M 3 0 0 7 2 28.57 J 5 1 20 6 3 50 J 3 0 0 7 4 57.14 A 4 1 25 6 3 50 S 4 0 0 7 1 14.28 O 3 1 33.33 7 2 28.57 N 3 0 0 8 2 25 D 3 0 0 9 2 22.22

254

Table (c): Monthly prevalence and intensity of trematodes of W. attu

Month Host Host Prevalence Total Intensity examined infested parasites January’11 11 2 18.18 6 3 February 10 2 20 3 1.5 March 11 1 9.09 3 3 April 10 0 0 0 0 May 10 2 20 1 0.5 June 11 0 0 0 0 July 10 2 20 4 2 August 10 0 0 0 0 September 11 0 0 0 0 October 09 2 22.22 4 2 November 10 2 20 2 1 December’11 11 5 45.45 3 0.6 January’12 11 0 0 0 0 February 9 3 33.33 4 1.3 March 10 2 20 1 0.5 April 11 2 18.18 3 1.5 May 10 2 20 3 1.5 June 11 0 0 0 0 July 10 2 20 4 2 August 10 0 0 0 0 September 11 2 18.18 5 2.5 October 10 0 0 0 0 November 11 0 0 0 0 December’12 12 1 8.33 2 2

255

Table (d): Monthly prevalence and intensity of trematodes of R. rita

Month Host Host Prevalence Total Intensity examined infested parasites January’11 33 6 18.18 15 2.5 February 34 9 26.47 17 1.9 March 35 9 25.71 18 2.0 April 34 4 11.76 18 4.5 May 31 5 16.12 26 5.2 June 34 6 17.65 16 2.7 July 33 12 36.36 14 1.2 August 32 9 28.12 12 1.3 September 35 6 17.14 17 2.8 October 33 9 27.27 6 0.6 November 35 9 25.71 15 1.7 December’11 33 9 27.27 18 2.0 January’12 24 5 20.83 17 3.4 February 25 6 24.00 12 2.0 March 22 6 27.27 16 2.7 April 23 5 21.74 18 3.6 May 24 3 12.50 19 6.3 June 23 6 26.09 12 2.0 July 29 10 34.48 7 0.7 August 26 7 26.92 13 1.9 September 28 5 17.86 11 2.2 October 26 5 19.23 10 2.0 November 24 5 20.83 18 3.6 December’12 24 5 20.83 18 3.6

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Table (e): Monthly prevalence of acanthocephalans of W. attu

Month Host E. kushiroense P. ophiocephali A. aculeatus P. umbellatus examined Host prevalence Host prevalence Host prevalence Host prevalence infected infected infected infected January’11 11 0 0 0 0 0 0 0 0 February 10 0 0 0 0 0 0 3 30 March 11 0 0 0 0 1 9.09 0 0 April 10 1 10 0 0 0 0 0 0 May 10 0 0 0 0 3 30 0 0 June 11 0 0 1 9.09 0 0 1 9.09 July 10 0 0 0 0 0 0 0 0 August 10 0 0 0 0 2 20 0 0 September 11 0 0 1 9.09 0 0 0 0 October 09 0 0 0 0 0 0 1 11.11 November 10 0 0 0 0 0 0 0 0 December’11 11 2 18.18 2 18.18 0 0 0 0 January’12 11 0 0 0 0 0 0 2 18.18 February 09 2 22.22 2 22.22 0 0 0 0 March 10 0 0 0 0 2 20 0 0 April 11 0 0 0 0 0 0 0 0 May 10 1 10 1 10 0 0 0 0 June 11 0 0 0 0 0 0 0 0 July 10 0 0 0 0 0 0 1 10 August 10 0 0 0 0 1 10 0 0 September 11 0 0 0 0 0 0 0 0 October 10 0 0 0 0 0 0 0 0 November 11 0 0 0 0 2 18.18 0 0 December’12 12 0 0 1 8.33 0 0 3 25

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Table (f): Monthly prevalence of acanthocephalans of R. rita

Month Host C. magnum C. alaskense C. strumosum examined Host prevalence Host prevalence Host prevalence infected infected infected January’11 33 1 3.03 0 0 1 3.03 February 34 1 2.94 1 2.94 0 0 March 35 0 0 0 0 1 2.86 April 34 1 2.94 0 0 1 2.94 May 31 0 0 1 3.22 0 0 June 34 1 2.94 4 11.76 1 2.94 July 33 0 0 0 0 2 6.06 August 32 1 3.13 0 0 0 0 September 35 0 0 1 2.86 1 2.86 October 33 1 3.03 0 0 0 0 November 35 3 8.57 1 2.86 0 0 December’11 33 0 0 0 0 1 3.03 January’12 24 0 0 1 4.16 0 0 February 25 1 4.00 0 0 0 0 March 22 0 0 1 4.54 1 4.54 April 23 1 4.35 0 0 0 0 May 24 1 4.16 2 8.33 0 0 June 23 0 0 1 4.35 0 0 July 29 4 13.79 3 10.34 2 6.89 August 26 0 0 1 3.85 1 3.85 September 28 1 3.57 0 0 1 3.57 October 26 1 3.85 0 0 0 0 November 24 0 0 0 0 0 0 December’12 24 0 0 1 4.16 0 0

258

Table (g): Temperature, Rainfall and Humidity in different months (Jan’ 11 – Dec’ 12)

Rainfall Humidity (%) Month Temperature(◦ c) (mm) January 27.8 0 99 February 31 0 93 March 34.5 14 93 April 35.8 49 93 May 35.3 25 96 June 36 56 97 July 35.4 84 97 August 35 94 97 September 36.2 36 96 October 34.5 40 95 November 32.4 0 97 December 30 0 97 January 28.5 7 96 February 33 1 92 March 37.3 36 96 April 37.1 62 96 May 36.2 53 94 June 36.7 56 94 July 34.3 51 100 August 34.5 54 97 September 36.5 23 98 October 34.4 13 97 November 32.4 24 97 December 28.5 5 99

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Table (h): Biochemical components in different months in W. attu

Month Moisture Protein Carbohydrate Fat Ash January 74.76 15.11 6.77 2.29 0.9 February 74.99 15.24 6.83 2.11 1 March 74.39 15.33 6.66 2.19 1.02 April 74.41 15.07 6.92 2.31 1 May 74.97 15.29 6.69 2.32 1 June 74.78 15.31 6.9 2.34 1.03 July 74.77 15.26 6.98 2.13 1 August 74.68 15.34 6.94 2.44 1.01 September 74.57 15.37 6.86 2.43 1.02 October 73.92 15.19 6.99 2.45 1.06 November 74.4 15.41 6.96 2.47 1.02 December 74.22 15.23 6.99 2.41 0.97 January 74.47 15.42 6.89 2.46 1.02 February 74.87 15.27 6.95 2.29 1.03 March 74.64 15.21 6.88 2.34 1.06 April 74.39 15.44 6.95 2.42 1.01 May 73.32 15.39 6.93 2.36 1.01 June 74.04 15.23 6.97 2.26 1.04 July 74.26 15.35 6.87 2.21 0.98 August 73.93 15.16 6.86 2.45 0.99 September 74.95 15.37 6.91 2.51 1.02 October 74.39 15.29 6.85 2.24 1.03 November 74.44 15.13 6.97 2.34 1.01 December 74.96 15.31 6.84 2.39 1.01

260

Table (i): Biochemical components in different months in R. rita

Month Moisture Protein Carbohydrate Fat Ash January 73.76 16.39 3.29 5.55 1.09 February 73.71 16.44 3.21 5.54 1.06 March 73.66 16.33 3.19 5.66 1.02 April 73.41 16.57 3.27 5.47 1.11 May 73.57 16.69 3.32 5.69 1.08 June 73.78 16.31 3.34 5.49 1.03 July 73.77 16.26 3.23 5.51 1.19 August 73.68 16.34 3.14 5.34 1.01 September 73.57 16.37 3.26 5.56 1.03 October 73.92 16.49 3.25 5.48 1.06 November 73.44 16.41 3.33 5.66 1.11 December 73.22 16.51 3.41 5.33 1.13 January 73.47 16.42 3.32 5.53 1.09 February 73.75 16.47 3.28 5.64 1.29 March 73.64 16.52 3.34 5.38 1.18 April 74.39 16.44 3.23 5.26 1.14 May 73.32 16.39 3.36 5.39 1.16 June 73.04 16.43 3.26 5.37 1.14 July 73.26 16.35 3.24 5.49 1.16 August 73.93 16.61 3.21 5.46 1.23 September 73.83 16.66 3.26 5.48 1.12 October 73.39 16.42 3.24 5.55 1.16 November 73.44 16.47 3.29 5.77 1.12 December 73.69 16.51 3.21 5.64 1.17

261