Evaluating growth, production and economics of a new candidate species Labeo bata in cages: A regional model for table fish production in floodplain wetlands of North East India

Indian minor carp Labeo bata fingerlings were reared in square shaped cages at different numbers to evaluate the effect of stocking density on growth, production and economics. Fifteen cages (5 x 5 x 2 m each) were installed in deeper areas (6-8 m) of Samaguri beel (a seasonally-flooded floodplain wetland) of Assam, India. The cages were stocked with L. bata (mean length 11.93 +/- 0.20 cm; mean weight 13.05 +/- 0.77 g) at five different stocking densities of 10 (SD10), 20 (SD20), 30 (SD30), 40 (SD40) and 50 (SD50) fingerlings m(-3) in triplicates. Fish were fed with floating pellets containing 32% CP at 3-5% body weight twice-a-day for six months. Density-dependent growth was evident from the results as growth of fish decreased with increasing stocking densities; the specific growth rate of the fish at SD10, SD20, SD30, SD40 and SD50 were 1.03 +/- 0.02, 0.88 +/- 0.01, 0.84 +/- 0.02, 0.67 +/- 0.02 and 0.52 +/- 0.01 with corresponding weight gain percent of 533.3 +/- 13.41, 385.8 +/- 10.73, 353.3 +/- 14.17, 232.2 +/- 8.08 and 155.9 +/- 5.38, respectively. However, the highest net yield of fish was achieved at SD30 (50.8 kg cage(-1)), which was significantly higher than other stocking densities. Also, economic analysis demonstrated highest benefit-cost (B:C) ratio at 30 fish m(-3) (1.44). Results indicated decreased fish yield at lower densities though the individual growth rate of fish was higher. On the other hand, fingerling stocking more than 30 fish m(-3) was uneconomical because of lower individual growth rate. Hence, a stocking density of 30 fish m(-3) could be considered as optimum for production of L. bata table fish in cages. The study generated new and critical information on species diversification in cage aquaculture for tropical floodplain wetlands.