Iranian Journal of Fisheries Sciences 14(1) 1-14 2015 Development of breeding and fingerling production techniques for endangered long-whiskered catfish Sperata aor in captivity Aminur Rahman M.1; Ara R.2; Amin S.M.N.2; Arshad A.1, 2 Received: September 2013 Accepted: September 2014 Abstract An experiment was undertaken to develop a suitable seed production technique for Sperata aor in captivity. Naturally produced fry of aor was reared at different densities in nine nursery ponds 0.012 ha in size with an average depth of 0.8 m each. Three stocking densities tested, each of which was triplicated. Fry of aor stocked at 100,000/ha was designated as treatment-1 (T1), 150,000/ha as treatment-2 (T2) and 200,000/ha as treatment-3 (T3). All stocked fry were from the same age group with mean length and weight of 1.78 ± 0.28 cm and 0.24 ± 0.05 g, respectively. Fry in all the treatments were fed with SABINCO nursery feed (32.06% crude protein) for the first 14 days and starter-I (31.53% crude protein) for days 15 to 56. Physico- chemical parameters and plankton population of pond water were within the optimal level being better in T1 than those in T2 and T3. Growth in terms of final weight and length, weight and length gain, specific growth rate, daily growth rate, and survival of fingerlings were significantly higher in T1 followed by T2 and T3. Food conversion rate was significantly lower in T1 than in T2 and T3. Significantly higher number of fingerlings was produced in T3 than those in T2 and T1. Despite this, consistently higher net benefits were achieved from T1 than from T2 and T3. This is the first time report that stocking of 100,000 fry/ha appears to be the most suitable density for rearing of aor fingerlings in nursery ponds. Keywords: Sperata aor, Fry, Stocking density, Fingerling, Growth, Production 1-Laboratory of Marine Biotechnology, Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 2 - Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia *Corresponding author email: [email protected] 2 Aminur Rahman et al., Development of breeding and fingerling production techniques for … Introduction using inducing agents, are sensitive to water The long-whiskered catfish S. aor quality changes and are easily stressed (Actinopterygii: Siluriformes: Bagridae) is (Rahman et al., 2005a). Therefore, locally known as “Ayre or Aor” in hatcheries face difficulties in synchronizing Bangladesh (Rahman, 2005). It is one of the maturity between male and female brood commercially important freshwater catfish, stock of this fish and a lack of naturally and was once abundant in canals, rivers, collected or artificially produced seeds for floodplains, inundated fields, swamps, stocking (Muchlisin et al., 2004). ditches, ponds and reservoirs in In the past, Aor was abundantly Bangladesh, Pakistan, Nepal, India and available in Bangladesh, but in recent years, Myanmar (Jayaram, 1977, 2002; Jhingran, the natural habitats and spawning grounds 1991; Talwar and Jhingran, 1991; Ferraris of this bagrid catfish have been severely and Runge, 1999; Menon, 1999; Rahman, degraded due to poor management, 2005). The longest specimen measuring 94 increasing water pollution, destruction of cm in total length and weighing about 5.0 spawning grounds and over-fishing. As a kg was recorded from the Gacher Dahar result, natural stock of this important Bill fishery in Sylhet district of Bangladesh fishery is declining at a daily rate (Rahman (Rahman, 2005). It has been considered as et al., 2005a). The International Union for one of the most admired edible fish among Conservation of Nature and Natural indigenous catfish species due to excellent Resources (IUCN), listed S. aor as one of taste and high market demand (Tripathi, the endangered native catfish species in 1996). Bangladesh (2000). While, very few work The fish is carnivorous in nature and have reported on the taxonomy, biology, readily feeds on live or frozen food, smaller population characteristics and distribution fishes, shrimps, frogs, snakes, insects, patterns of S. aor (Jhingran, 1991; Talwar earthworms, tadpoles, crustaceans and and Jhingran, 1991; Rahman, 2005; Khan et prepared foods such as pellets al., 2011; Sarkar et al., 2013), no systematic (Arunachalam et al., 2000; Rahman, 2005). attempts have been made to develop In natural habitat, it builds nest during breeding protocols and culture techniques. reproductive period and guard its nest, and A few attempts have recently been made on normally breeds twice a year from May to induced breeding without success (Rahman July and from September to November et al., 2005a). Because of the non- (Talwar and Jhingran, 1991; Rahman et al., availability of seeds in natural waters, not 2005a). Absolute fecundity of this fish much success has been achieved in varies from 16,147 to 105,760 with a size commercialization of aquaculture and range between 34.60 and 48.60 cm, with conservation of this species (Rahman et al., egg diameter estimated between 0.90-1.40 2005a). Hence, it is now most important to mm (Rahman unpub. data). There are conserve this endangered species in a several reasons for the lack of aquaculture sustainable manner. In the present study, of the tropical bagrid catfishes. These fishes aor was bred for the first time under natural are difficult to make spawn artificially propagation techniques and the produced Iranian Journal of Fisheries Sciences 14(1) 2015 3 fry were reared at different stocking were collected from the holes by complete densities to optimize the best density drying of the pond and then reared for 8 considering the highest growth, production weeks in nursery ponds. and benefit of the endangered S. aor fingerlings in a nursery management Rearing of fry and fingerlings in nursery system. ponds The collected fry of aor was reared for 8 Materials and methods weeks from 10 June to 5 August in nine Broodstock collection and rearing earthen nursery ponds with a surface area of In total, 100 individuals of adult aor 0.012 ha and an average depth of 0.8 m weighing from 700 to1250 g were collected each. To assess optimum growth and from the Brahmaputra river-basin and survival of fingerlings, different stocking floodplains of greater Mymensingh region densities of fry (No./ha) viz., 100,000 (T1), during January-February, 2007. 150,000 (T2), and 200,000 (T3) were tested Immediately after collection, the fishes with three replicates for each. After were transported to Freshwater Station, dewatering, quicklime (CaCO, 250 kg/ha) Bangladesh Fisheries Research Institute, was spread over the pond bottom. Ponds Mymensingh and then reared in earthen were then filled with ground water and ponds with supplementary feeds fertilized with organic manure (cowdung, comprising rice bran (30%), mustard 2500 kg/ha). Seven days after manure oilcake (29%), fish meal (40%) and application, the pond water was sprayed vitamin-premix (1%) at the rate of 5-6% of with dipterex (2, 22-Trichloro-1-Hydroxy the estimated biomass. The pond was Ethyl Phosphate, manufactured by Ciba fertilized at fortnightly intervals with cow Ltd.) at the rate of 1.0 ppm to kill harmful dung (1,000 kg/ha) and Urea & TSP (50 insects and pathogens. Fry having an kg/ha). average length of 1.78± 0.28 cm and weight of 0.20±0.03 g were then stocked in the Natural propagation nursery ponds. For stimulating natural propagation of aor, Fry in all the experimental ponds were artificial holes (nests) were made on the fed with commercial Saudi Bangla pond bottom. Each hole was 0.7 m in (SABINCO) fish feed viz., nursery (32.06% diameter and 0.3 m in depth. A total of 30 crude protein) for the first 14 days and holes were made in a pond having an area starter-I (31.53% crude protein) from days of 0.08 ha. Three months before the onset 15 to 56. The rate of feeding was 14% of of the breeding season, 30 pairs of Aor the estimated body weight of fry for the first breeders (700-1250 g) were stocked in the two weeks, 12% for the second two weeks, pond and fed with supplementary feed as 10% for the third two weeks and 8% for the stated above. Fresh ground water was fourth two weeks. After stocking, the ponds supplied everyday to maintain natural were fertilized with cow dung (1000 kg/ha) phenomena for breeding. During mid May at weekly intervals to hasten the primary to early June 2007, a total of 19,428 Aor fry productivity of the ponds. 4 Aminur Rahman et al., Development of breeding and fingerling production techniques for … Physico-chemical parameters of pond water fingerlings were then estimated and were monitored weekly between 09.00 and compared among the treatments. 10.00 h. Temperature (oC) and dissolved oxygen (mg/L) were determined directly by Data analysis a digital water quality analyzer (YSI, model The data on growth, survival, production, 58, USA), pH by a digital pH-meter water quality parameters and plankton (Jenway, Model 3020, UK) and abundance of different treatments were transparency (cm) by a secchi disc and tested through one-way analysis of variance ammonia nitrogen by a HACH water (ANOVA) using ‘Stat View’ version 4.0 analysis kit (DR 2000, USA). Total followed by Duncan's New Multiple Range alkalinity was measured following the test (Duncan, 1955). The level for statistical standard method (Stirling, 1985; APHA, significance was set at 0.05%. A simple 1992). cost-benefit analysis was implemented to Quantitative and qualitative estimates of estimate the net benefits from different plankton in the nursery ponds were taken treatments.