Effect of stocking density on survival, growth and production of indigenous Labeo calbasu (Hamilton, 1822) in nursery ponds

Effect of stocking densities on the growth, survival and production of kalibaus, Labeo calbasu fry and fingerlings were tested in a single-stage nursery rearing system. The experiment was conducted for a rearing period of six weeks in nine earthen nursery ponds having an area of 0.028 ha each. Four-day-old hatchlings stocked at 0.6 million/ha were designated as treatment T1­, 0.8 million/ha as treatment T2 and 1.0 million/ha as treatment T3. At stocking, all hatchlings were of the same age with a mean length and weight of 6.50±0.01cm and weight of 0.007±0.00g, respectively. Physico-chemical parameters and plankton populations were at the optimum level for the culture period. Highest weight gain was observed in treatment T1 and lowest in treatment T3. Final length, final weight and survival of fingerlings also followed the same trends as weight gain. Fingerlings in treatment T1 produced significantly higher specific growth rate than treatment T2 and T3. Feed conversion ratio was significantly higher in treatment T1 followed by T2 and T3. Significantly higher number of fingerlings was produced in treatment T3 than in T2 and T3. Overall, highest growth, survival and net benefits of fingerlings were obtained in the treatment T1 at a density of 0.6 million hatchlings/ha. Therefore, of the three stocking densities, 0.6 million hatchling/ha appears to be the most suitable stocking density for nursing and rearing of L. calbasu fry and fingerlings.