Effect of stocking density on growth and survival of endangered Mystus bleekeri (Day, 1877) in nursery system

The effect of stocking densities on growth, survival and production of gulsa tengra, Mystus bleekeri fry and fingerlings were practiced in a nursery rearing system. The experiment was designed with 3 treatments and 3 replications and conducted for seven weeks in nine earthen nursery ponds of 0.032 ha each. Four-days-old hatchlings were stocked at 0.60 million/ha, 0.80 million/ha and 1.0 million/ha was designated as treatment T1¬, T2 and T3. At stocking, hatchlings had a mean length and weight of 0.91±0.01 cm and 0.001±0.01g. Hatchlings in all treatments were fed with 32.90% crude protein and 8.80% crude lipid. Physico-chemical parameters (temperature, transparency, pH, dissolved oxygen and total alkalinity) and plankton populations were at the optimum level for fish culture. The highest weight gain (3.16±0.66g) was measured in treatment T1 and the lowest (2.01±0.88 g) in treatment T3. Final length, final weight and survival of fingerlings followed the similar trends as weight gain. Specific growth rate and feed conversion ratio was significantly better (P<0.05) in treatment T1 followed by treatment T2 and T3. Survival rate was also higher (P<0.05) in treatment T1 than in treatment T2 and T3, respectively. Despite this, higher economic returns (Bd Tk. 367733/ ha) were observed for treatment T1 than from treatment T2 and T3.