Impact of stocking density on growth, feed utilization and survival of cage reared minor carp, Labeo bata (Hamilton, 1822) in Maithon reservoir, India

Abstract

The present study was carried out to evaluate the effects of stocking density on growth performance of stunted fingerlings of Labeo bata in cages for a period of 180 days, at Maithon reservoir, Jharkhand, India. L. bata (8.80 + 0.67 cm; 6.18 ± 1.32 g) were reared at three stocking densities of 50 fingerlings m􀀀 3, 75 fingerlings m􀀀 3, and 100 fingerlings m-􀀀 3 in triplicates in Galvanized Iron (GI) cages. Fishes were fed with floating pelleted feed (CP: 32%, CL: 4%) @ 5–3% of the body weight twice a day. L. bata reared at density of 50 fingerlings m􀀀 3 showed significantly higher (p < 0.05) specific growth rate (SGR) (1.08 ± 0.02) and survival (84%) than those reared at 75 fingerlings m􀀀 3 and 100 fingerlings m􀀀 3. No significant differences (p > 0.05) in SGR were found between the densities 75 fingerlings m􀀀 3 and 100 fingerlings m􀀀 3. The growth and survival were lowest at stocking density of 100 fingerlings m􀀀 3. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were highest i.e. 1.95 ± 0.08 and 1.65 ± 0.06 respectively at 50 fingerlings m􀀀 3. Condition factor (K) varied significantly (p < 0.05) among the treatments and was significantly better at 50 fingerlings m􀀀 3 after 180 days. Coefficient of variation (CV) was lowest at 50 fingerlings m􀀀 3, but did not vary significantly (p > 0.05) among the treatments. Length weight relationship exhibited positive allometric growth of L. bata in cages. In spite of higher biomass produced at higher densities, the benefit cost ratio (BCR) was highest at stocking density of 50 fingerlings m􀀀 3 (1.57). Overall, our results indicate that L. bata exhibit better growth and condition at lower stocking density indicating that higher densities negatively affect the growth. The fish in cages exhibited growth comparable to ponds and open waters. It can be concluded that the stocking density of 50 fingerlings m􀀀 3 is the most desirable and economic for L. bata fingerlings to achieve table size in the cage culture system.