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

Abstract

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 °C in the pond and 23.2 to 28.9 °C 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.