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Larval Rearing of an Endangered Fish of Northeast India, Ompok Bimaculatus (Bloch) for Future Conservation

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International Journal of Aquaculture, 2014, Vol.4, No.10, 64-66 http://ija.sophiapublisher.com

A Letter Open Access Preliminary Studies on Larval Rearing of an Endangered Fish of Northeast India, Ompok Bimaculatus (Bloch) for Future Conservation P.K. Pradhan1, Debtanu Barman2 1. National Bureau of Fish Genetic Resource (NBFGR), Lucknow, 226002, India 2. Center for Aquaculture Research & Development (CARD), St. Xavier’s Vocational Training Center, Don Bosco, Bishramganj, Tripura, 799103, India Corresponding author email: [email protected] International Journal of Aquaculture, 2014, Vol.4, No.10 doi: 10.5376/ija.2014.04.0010 Received: 11 Nov., 2013 Accepted: 18 Dec., 2013 Published: 22 Jan., 2014 Copyright © 2014 Pradhan and Barman, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Pradhan and Barman, 2014, Preliminary Studies on Larval Rearing of an Endangered Fish of Northeast India, Ompok Bimaculatus (Bloch) for Future Conservation, International Journal of Aquaculture, Vol.4, No.10: 64-66 (doi: 10.5376/ija.2014.04.0010)

Abstract In the present research work, an attempt was made to standardize the larval rearing technique of Ompok bimaculatus (Pabda), an endangered catfish of North-East India for sustainable conservation & diversification of aquaculture in general. Two days old yolk sack larvae were reared in the laboratory conditions for a period of 12 days and survival percentage at the end of the experimental period was recorded. The results of the study showed that it was possible to obtain a survival percentage ranging from 47% - 62 %. Further, rearing of larvae in cement tanks for a period of 30 days resulted in a survival percentage of about 90%. The results demonstrate the potential to improve larval survival by providing apt food and water quality conditions. Keywords Ompok bimaculatus; Larval rearing; Survival and Conservation

Introduction the seed produced under controlled conditions and Ompok bimaculatus, a non-air breathing silurid fish creation of opportunity for the fishers to undertake the with the highest growth amongst the three species culture of this species. For the successful culture under the genus Ompok namely Ompok pabda, O. operation development of reliable breeding and larval pabo and O. bimaculatus and these fish are commonly rearing technique is essential. known as Pabda. The species has been categorized as Recently, Government of Tripura has declared the fish an endangered fish species and is listed amongst the (Ompok bimaculatus) as “STATE FISH” and reported 91 endangered fish species of India as per the that “it is an important fish of the state and is in International Union for Conservation of Nature and endangered condition and needs more attention for Natural resources (IUCN) criteria. Most importantly, conservation and propagation”. Eating of Pabda fish amongst the 91 endangered species, 31 species have (particularly in Tripura) is generally considered as the been reported to be from northeast and out of 31 status symbol and the species is the most expensive species, 11 species having been reported to be food fish (Rs 350-450/-/kg). endemic to the region. Ompok bimaculatus is amongst the 11 such species. Further, it has been reported that Though the State Fisheries Department was able to Ompok bimaculatus wild population has undergone a breed the fish under controlled conditions, very low steady decline (>50%) over the last 10 years and the survival during larval rearing was reported as the species is facing high risk of extinction in the wild in major limiting factor. Several other researchers near future (Conservation Assessment and Management working on the larval rearing of pabda in other part of Plan workshop, 1997; Sarkar and Ponniah, 2000; the country (Shreedhar et al., 1998; Bhowmik and Ponniah and Sarkar, 2000).The depletion of natural Ayyappan, 2000; Bhowmik et al., 2000; Chakraborty resources at an alarming rate warrants immediate et al., 2006; Hussain, 2006; Chakroborty et al., 2007) action to arrest and reverse the trend at the earliest. also have reported that during larval rearing of pabda, Aquaculture can help in conservation of this fish very poor larval survival is the common problem species through various ways: reduction on fishing noticed. Hence, in the present study, an attempt was pressure by partly meeting the consumer requirement made to standardize the larval rearing technique of from culture, restocking of natural water bodies with pabda (Ompok bimaculatus). 64

International Journal of Aquaculture, 2014, Vol.4, No.10 64-66 http://ija.sophiapublisher.com

1 Materials and Methods libitum, twice daily (7am and 4 pm) and the The adult fish were collected from the natural concentrations of the live feed (artemia nauplii/ resources (Rudrasagar Lake, Sepahijala District, zooplankton) in the aquaria were adjusted depending Tripura) in the month of May,2007 and stocked in the on the residual live feed concentration in the tank. earthen ponds (0.03ha area) of the College of Every day, about 30-40% of the water was exchanged Fisheries, Lembucherra, Tripura. The fish were fed with fresh clean pond water (stored in a FRP tank). with small fish, prawn and artificial feed (mixture of The larval rearing was carried out for a period of 12 rice bran, mustard oil cake and dry fish powder) ad days and at the end of 12 days, the surviving larvae libitum and reared for a period of two months. In the were counted and survival percentage was calculated. last week of July, 2007 4 numbers of fully matured Ten numbers of larvae from each of the tank were male and female fish (each) were selected. The female collected and there individual weight and length were fish were injected with ovaprim @ 1.0ml/kg body taken. The survival percentage and the growth data weight while the male fish were injected with ovaprim (length and weight) were subjected to chi-square and @ 0.5ml/kg body weight. The average weight of the t-test, respectively for finding out the significant broodfish was in the range of 40-45gm. After injection, difference between two different groups i.e. fed with the fish were kept in a breeding hapa and maintained zooplankton and artemia nauplii. Further, 125 in cement cistern having a mild water flow. After 8 numbers of 12 days old larvae were stocked in a hours of injection, the fish were taken out of the hapa, 2 and the male fish were dissected and the testes were cement cistern of 50m area having 6 inch soil bed and removed and sperm suspension was prepared by prepared in advance following the procedure of macerating the testes in the physiological saline in a nursery ponds. The larvae were reared in the cement mortar and pestle. The female fish, in which the eggs cistern for period of 30 days and were fed with a were oozed out easily with gentle pressure on the mixture of rice bran, mustard oil cake and dry fish abdomen, were selected and stripped and eggs were powder once daily. At the end of thirty days, all the collected in a clean enamel tray and fertilized with fish were harvested counted and length and weight of the sperm suspension by gentle mixing with help of a fish were taken before stocking into stock pond. feather. The fertilized eggs were washed with clean 2 Results and Discussion water and kept in a flow through system for hatching. Survival percentage and growth of larvae during the The eggs started hatching after 20 hours and within 12 days experimental period is presented in Table 1. 24 hours all the eggs hatched (at a water temperature of 27℃). The hatchlings were kept on the flow Average survival percentage of the group of larvae fed through system. with artemia was 62% where those fed with zooplankton showed a survival percentage of 47% and Two days old hatchlings were collected randomly and the statistical analysis (chi square test) indicated that stocked in glass aquaria containing 50 liters clean the difference in survival between the two groups pond water each with 50 numbers of larvae. were significant (p<0.01). Average growth in terms of Altogether six aquaria were used and larvae stocked in length and weight were 25.3 mm and 112mg, three aquaria were fed with freshly hatched artemia respectively for the group of larvae fed with artemia nauplii and larvae stocked in rest three aquaria were and for the group of larvae fed with zooplankton, fed with filtered zooplankton collected from well average growth in terms of length and weight were 24.3 prepared fertilized ponds. The larvae were fed from mm and 94mg, respectively and statistical analysis the third day after hatching (i.e. on the second of (t-test) indicated that the growth of the group of larvae stocking in the aquaria). The larvae were fed ad fed with artemia nauplii was significantly (p<0.05)

Table 1 Mean growth parameters and survival percentage with ± SE (Standard Error, n=3) for Ompok bimaculatus fry Treatment Mean Length (mm) Mean Final Weight (mg) Mean Survival (%) Initial Final Fed on Zooplankton 2.33±0.07 24.33±0.33a 94±6.51 a 47.3±5.92 a Fed on Artemia nauplii 2.33±0.07 25.33±0.33b 112±8.08 b 62.7±5.21 b Note: Values with different alphabet in a column are significantly different at 0.05≤p<0.08 65

International Journal of Aquaculture, 2014, Vol.4, No.10 64-66 http://ija.sophiapublisher.com

different from that of the larval group fed with conditions that too in earthen nursery ponds. However, zooplankton. Average survival percentage of the 12 such encouraging results indicate that by changing the days old larvae after 30 days of rearing in the cemented management practices, there is possibility to improve tank was 90% and the mean growth in terms of length survival and growth. Future, studies should be under and weight were 7.5cm and 3.34gm, respectively. taken to develop practical systems that can be adopted by seed producers. There are very few reports on the breeding and seed production of pabda (Shreedhar et al., 1998; Hussain, Acknowledgements 2006, Chakraborty et al., 2006; 2007), but the survival The study was carried out under an Intramural Research Project percentage of larvae has not been reported by most of and the financial assistance for the project was provided by the the researchers except Hussain (2006), who has Central Agricultural University, Imphal. The authors also want reported 7.89% survival in a rearing period of 9 to 19 to express their sincere thanks to the unknown referees for their days growth. Sridhar et al. (1998) and Chakraborty critical comments which helped to improve the manuscript. et al. (2006 & 2007) have reported that, in the larval References rearing of pabda, high mortality rate in the initial Bhowmik M.L., and Ayyappan S., 2000, Biodiversity conservation in stages of seed raising continues to cause a major Northeast India-a challenge, In: Fish Biodiversity of Northeast India, (Eds. A.G.Ponniah and U.K.Sarkar). NBFGR, NATP Publ.2: management problem. 71-72. Bhowmik M.L., Mondal S.C., Chakrabarti P.P., Das N.K., Das K.M., Saha It has to be noted that Hussain (2006) and all other R.N. and Ayyappan S., 2000, Captive breeding and rearing of Ompok researchers had carried out the study in the earthen pabda –a threatened species. In: Fish Biodiversity of Northeast India, (Eds. A.G.Ponniah and U.K.Sarkar). NBFGR, NATP Publ.2: 120-121. nursery pond but the present experiment was carried Chakrabarty M.N., Mondal S.C., and Chakrabarty P.P., 2006, Mass seed out in aquaria. This facilitated easy feeding and production of pabda and their farming- a challenging step for sustainable utilization of the vulnerable fish species. Fishing Chimes, allowed the larvae to pray on the food. In addition to 26 (1): 133-135. survival the length and weight attained by the larvae Chakrabarty M.N.; Mondal S.C., and Chakrabarty P.P., 2007, Artificial were also satisfactory. Shreedhar at al. (1998) had breeding, seed production, and rearing of butterfish Ompok pabda-a significant milestone in technology advancement. Fishing Chimes, reported that at 12 days post hatching the growth of 26(10): 134-136. larvae were about 8-12 mm, but, in the present study, CAMP, 1997, Conservation Assessment and Management Plan (CAMP) workshop for freshwater fishes of India, NBFGR, Lucknow, 1997: 327. at the end of 12 days post hatch, the growth of larvae Hussain A., 2006, Seed production of Ompok pabda in hatcheries of C G were 24-25 mm and this was higher than the growth Cooperative fish federation. Fishing Chimes, 26 (1): 136-139. after 30 days of post hatching reported by the same Ponniah A.G., and Sarkar U.K., 2000, Overview of fish biodiversity of Northeast India, In: Fish Biodiversity of Northeast India, (Eds. author. Further, at the end of rearing period of 30 days A.G.Ponniah and U.K.Sarkar). NBFGR, NATP Publ.2: 1-10. in the cement tank a survival percentage of about 90% Sarkar U.K., and Ponniah A.G., 2000, Evaluation of Northeast Indian Fishes for their potentials as cultivable, sport and ornamental Fishes along was achieved and the larvae had achieved a growth of with their conservation and endemic status. In: Fish Biodiversity of about 3.5 gm and length of 7.5cm. As mentioned Northeast India, (Eds. A.G.Ponniah and U.K.Sarkar). NBFGR, NATP earlier, it has to be noted that the present study was Publ.2: 11-30. Shreedhar S., Vijoykumar C., and Haniffa M.A., 1988, Induced spawning carried out in the aquaria and cement tank while other and establishment of a captive population of an endangered fish Ompok researchers have carried out their studies in field bimaculatus. Current Science, 75: 1066-1068

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