Production of silver perch (Bidyanus bidyanus) fingerlings at three stocking densities in cages and tanks

摘要

Silver perch fry (mean weight 2.3 g) were stocked at densities of 50, 100 or 200 fish/m(3) in replicated cages or tanks (both 1 m(3)) and cultured for 140 days. The cages were floated in an aerated, 0.32-ha earthen pond and the tanks were on a flow-through system at 5 l/min. Fish were fed a formulated diet containing 35% crude. protein. Water temperatures ranged from 23.9 to 31.0 degreesC in the pond and 23.2 to 28.9 degreesC in the tanks. Mean survival ranged from 92.0% to 99.5%. Growth and condition were not affected by stocking density in either facility; however, fish stocked in cages grew significantly (P < 0.01) faster (specific growth rate [SGR] 2.80%/day, absolute growth rate [AGR] 0.8 g/fish/day), to a larger size (mean weight 116.3 g) and were in better condition (K = 2. 0) than fish cultured in tanks (2.15%/day, 0.3 g/fish/day, 46.6 g, 1.8). Production of fingerlings was significantly (P < 0.01) affected by stocking density and rearing facility, and the maximum production rate achieved was 21.0 kg/m(3) in cages stocked with 200 fish/m(3). An overall FCR of 2.0 of fish in cages was significantly (P < 0.05) lower than an FCR of 2.5 in tanks. The results of this study suggest that cages are more suitable than tanks in a flow-through system, and are a viable alternative to ponds for the culture of silver perch fingerlings