Journal of Zoology and Research (JZR) Vol. 2, Issue 2, Dec 2016, 1 - 6 © TJPRC Pvt. Ltd

FOOD AND FEEDING HABITS OF OXYURICHTHYS TENTACULARIS ,

GOBIIDAE (VALENCIENNES, 1837) FROM ASHTAMUDI LAKE - KERALA

R EMYA MOHAN & SHERLY WILLIAMS, E Enviro nmental Science, Aquaculture & Fish Biotechnology Lab , Departm ent of Zoology , Fatima Mata National College , Kollam , Kerala , India ABSTRACT

The food and feeding habits of Oxyurichthys tentacularis was studied from Ashtamudi Lake in Kollam district. Oxyurichthys tentacularis locally known as koozhali commercially one of the important food fish of Ashtamudi Lake. The fish is a member of Gobiidae family, and particularly a bottom feeder. The Dietary analysis showed that Oxyurichthys tentacularis is an o mnivore. The study revealed that fish does not prefer any specific food items. Feeding was mainly depends upon the availability of food items. Detritus and Crustaceans constituted the major food items.

KEYWORDS: Oxyurichthys tentacularis , Ashtamudi Estuary, Food a nd Feeding Habits

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Received: Aug 08, 2016 ; Accepted: Sep 09, 2016 ; Published: Sep 19, 2016 ; Paper Id.: JZRDEC20161 r i g i n

INTRODUCTION a l

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The study of food and feeding habits of commercially important fishes is i nevitable for understanding the r t i various aspects of biology such as growth, development, reproduction , migration and condition c l e

( Windell, and Bowen, 1978) . S tudy on food and feeding habits of fishes is one of the main aspects in its biolog ical study (Qasim, 1972). The spectrum of prey consumed by a species helps to define its fundamental niche (Hutchinson, 1957) . Extensive studies on feeding biology of fishes are available ( Brulé et al .,1994; Hyslop, 1980 ;Windell and Bowen, 1978; George et al ., 19 68; Nair, 1979 ; Dasgupta, 2004; Tandon (1962) ; Geevarghese (1976) ; Lekshmi et al ., 2010)

Members of the Gobiidae are small benthic fishes inhabiting a wide range of habitats in temperate and tropical regions (Nelson 1994) The Oxyurichthys tentacularis , a member of family Gobiidae , is one of the important food fish of Astamudi lake. Studies on Indian gobioid fishes are very few . Given the lack of biological or ecological data on this species the objective of this work was to study the food and feeding habi ts of Oxyurichthys tentacularis in the Ashtamudi lake of Kerala.

MATERIALS AND METHODS

The specimens of O. tentacularis were collected from Ashtamudi lake (8 o 53’ - 9 o 02’ N; 76 o 31’ - 76 o 41’ E) with the help of local fishermen by using cast net and gill net . A total of 430 guts (length range of fis h 10 cm to 17 cm were examined following the procedures suggested by Windell and Bowen (1978). The guts along with contents were removed and preserved in 5% formalin. The total length a nd fullness of the guts were recorded. The gut was exposed and the stomach contents were analyzed using the frequency of occurrence and point methods. For the frequency of occurrence, the number of stomachs containing food was quantified and expressed

www.tjprc.org [email protected] 2 Remya Mohan & Sherly Williams, E as a percentage of all non - empty stomachs. The intensity of feeding was assessed based on the state of fullness of the gut and the amount of food contained in it, and categorized as empty, poor, moderate (half - full gut), full and g orged (full and dilated gut) and were represented as stage I,II, III, IV and V respectively.

RESULTS AND DISCUSSION S

The present study showed a mixed diet composition such as Detritus, Crustacean, Bivalves, Green algae, Blue green algae, Diatoms , Polychaete worms, Fish scales and eggs revealed that the fish is predominantly an omnivore. Detritus and Crustaceans are invariably present in the stomach throughout the year and constitute the maximum quantity. So these two are the most pr eferred food items. Detritus (37.01%) is an assortment of different materials containing faecal tubes of invertibrates, soft bottom mud with sand, decaying plant and animal matter. Crustaceans (35.24%) consist of amphipods (majority) mainly Phortis sp., an d Talorchestia Ostracods and copepods include calanoid and cyclopoid copepods. Crustacean larvae mostly of prawns both penaeid and palaemonids. Bivalves occupied (11.62%) Diatoms ( Bacillariophyceae) ( 6.24%) were represented by pleurosigma ( most abundant) , fragillaria, Navicula, Nitzschia (prominent), Coscinodiscus, Synedra, Cocconema, Rhizosolena and Pinnularia. Blue green algae (3.21%) were represented mostly by Microcystis, Anabaena and Oscillatoria. Green algae ( 2.13%) consist of Spirogy ra, Closterium, Scenedesmus and Hormidium. Polychaetes ( 3.21 ) mainly includes Neries. Fish scales and egg (1.23%) were least choice, and they ingested accidentally. Seasonal variation , includes d etritus and Crustaceans are consistently present in the stomach throughout the year. Preference of detritus was high in A ugust, September, November and December and at the same time the crustacean preference was high in January, February, June, July and October. Diatoms show ed a season of occura nce. Polycheate worms seen sporadically.

Feeding in tensity and g astrosomatic Index shows a wide variation Pe rcentage of empty stomach (Figure 2) indicated lowest food intake during monsoon months (June - July) coinc iding with the breeding season and intense feeding during pre monsoon months. The presence of copepods, bivalves, eggs and micro - mollusks in the diet, although showing a relatively high frequency of occurrence, appears to be incidental. It has even been noticed that the same species may consume a variety of food from different localities which means that, some of the gobioid species have no food specificity . Since the food and feeding habits of this species has not been reported previously so it is very difficult to compare the present results with earlier results. But details are available on the feeding habits of other species of gobioids. Such information shows that they may range from near herbivorous to purely carnivorous, feeding on a wide variety of ingestible organisms from its habitat. The p resence of sand grains, and detritus in the diet was a sign of the benthic behaviour of the fish (Serajuddin, and Rustam 2005). The diets of many goby species also indicate that detritus and algae are common food types (Kinch 1979, Darcy 1980, 1981, Maciol ek 1981).

The occurrence of empty stomachs which is related with rapid rate of digestio n. It may be clear that the feeding intensity and diet composition of fish are apparently linked to the availability of food in the habitat (Bhatnagar and Karamchandani, 1970). P ercentage of empty stomach (Figure 2) indicated lowest food intake during monsoon months coinciding with the breeding season and intense feeding during premonsoon months (Jayaprakas and Nair, 1981) . Ompok bimaculatus and O. malabaricus show low feeding intensity during August and June may not be due to shortage of food items but due to the spawning season of the fish (Arthi et al., 2011). According to Menon & Chacko (1956) fishes feeding on filamentous algae, molluscs, worms, and whose guts contain sand grains in fair proportions are benthic feeders .

www.tjprc.org [email protected] Food and Feeding Habits o f Oxyurichthys t entacularis , 3 Gobiidae (Valencien nes, 1837) f rom Ashtamudi Lake - Kerala

CONCLUSIONS

If this characterization is to be relied upon, Oxyurichthys tentacularis is also a bottom feeder as with most of the gobioid fishes. These observations shows that availability of food in the habitat is the main factor that determines the feeding habits of some gobioids, and that such species have no food specificity.

REFERENC ES

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APPENDICES

Table 1 : Monthly Composition (%) of Food Items o f Oxyurichthys tentacularis i n Ashtamudi Lake During 2013 - 2014 No . Blue Green Polychaete Fish Scales Months of Detritus Crustacean Bivalves Green Diatoms Algae Worms and Egg Fish Algae August 35 54 .32 23 .36 1 6 .03 - 1.09 - 2.13 1.32 September 31 61.02 23.15 14.26 - 1.36 - - 0 .31 O c tober 34 3 1 .68 42.21 12.98 - - 9 .03 0.36 3.65 N ove mber 29 51.53 23.26 13.32 1.32 5.69 2.30 - 2.58 December 26 62.31 21.32 5.09 1.30 3.65 5.31 - 1.02 January 27 3 4.31 42.36 2.81 1.36 4.25 12.36 2.30 0.25 February 29 39 .31 40.36 11.41 2.10 1.32 - 5.20 0.30 March 34 13.21 27.21 10.77 3.24 3.64 15.62 1.03 1.24 Apr il 33 23 .31 21.56 19.36 5.31 15.32 13.25 1.89 - M ay 34 26 .69 33.21 15.7 2.61 9.63 9.30 1.54 1.32 June 32 13.21 61.32 23.17 - - - - 2.30 Ju l y 31 1 2 .30 66.32 17.31 - - - 1.39 2.68

Table 2 : Diet Composition o f Oxyurichthys tentacularis i n Ashtamudi Lake i n Lake during 2013 – 2014 Diet Composition Percentage Detritus 37 Crustacean 35 Bivalves 11 Green algae 2 Blue green algae 3 Diatoms 6 Polychaete worms 3 Fish scales and egg 1

www.tjprc.org [email protected] Food and Feeding Habits o f Oxyurichthys t entacularis , 5 Gobiidae (Valencien nes, 1837) f rom Ashtamudi Lake - Kerala Figure 1: Fullness of the Gut o f Oxyurichthys tentacularis i n Ashtamudi Lake During 2013 - 2014 (I – Empty, II – Poor, III – Moderate, IV – Full, V – Gorged)

Figure 2 : Diet Composition o f Oxyurichthys tentacularis i n Ashtamudilake during 2013 – 2014

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