EFFECT OF STOCKING DENSITY ON FRY SURVIVAL AND GROWTH OF SAHAR Tor putitora
Sahar (Tor putitora) is a high value indigenous fish species of Nepal. We achieved success in induced spawning of sahar using synthetic hormone in the sub-tropical climate of Nepal. An experiment was conducted for 90 days to determine the optimum density of sahar for fry rearing. Sahar fry of average initial weight 0.28 to 0.32 g were stocked at four different stocking densities in 2 m2 nylon hapas fitted in concrete tanks. The treatments were: 5 fish/m2 (T1); 10 fish/m2 (T2); 15 fish/m2 (T3); and 20 fish/m2 (T4). Each density treatment was replicated thrice. Fish were fed with commercial pelleted feed (32% CP) twice daily at 5% of the biomass. In situ water temperature, pH and dissolved oxygen were monitored weekly at 6.00-7.00 am.
The mean harvest weight and daily growth rate of fingerlings were highest in T1, intermediate in T2, and lowest in T3 and T4 (p˂0.05; Table 1). The condition factor, specific growth rate and survival rate were not affected by stocking density (p˃0.05). Temperature, pH and dissolved oxygen ranged from 28.5-31.5 oC, 7.3-9.6 and 6.0-9.5 mg/L, respectively. The present results demonstrated that sahar fry can be successfully reared up to density of 20 fish/m2 in nylon hapa with good survival and growth, although overall growth and harvested weight were considerably higher in the lowest density treatment.