Effect of stocking density and feeding rate on growth, hematological parameters and water quality in rearing of juvenile Bluga (Huso huso)

Growth, hematological parameters and water quality for great sturgeon (Huso huso), were determined at three different stocking densities and three feeding rates. Stocking density were 1, 1.5 and 2 kg m-2 and feeding rates were 1, 2, and 3% body weight day-1. Sturgeon were offered to 18 tanks and 3×3 experimental design was used with two replicates per treatment. Initial average body weights of the fish were 25 ± 1.5g and were hand-fed a pelleted commercial feed (44 % protein, 20% fat, and 7% ash) twice daily throughout the experiment period. After about 7 weeks of feeding, optimal feeding rate and growth performance was observed in 1 kg m-2 and 3% of body weight day-1 and there were significant difference interaction in stocking density and feeding rate between treatments (P<0.05). The results demonstrated that hematological parameters were not significantly different in all groups (P>0.05). No mortality was abserved during the experiment. Water quality including ammonia (NH3) and dissolved oxygen (DO) showed significant differences (P<0.05) among the treatments affected by different densites and feeding rates, while temperature and pH showed no significant difference (P>0.05). Results show that the optimum feeding rate and stocking density for fishes weighing 25 to 155 would appear at a feeding rate at 3% body weight day-1 with the stocking density 1 kg m-2.