Efect of dietary protein: fat ratios on metabolism, body composition and growth of juvenile pikeperch, Stizostedion lucioperca (L.)

The effects of diet composition (commercial trout feeds: 42.2-52.5% protein , and 14.0-22.0% fat) on growth rate, oxygen consumption, ammonia excretion and body composition were examined in juvenile pikeperch (initial total le ngth 16.5 cm, and body weight 42.5 g) reared in a water recirculation syste m for 28 days from day 128 to 156 posthatch. There were no significant diff erences in fish growth, condition, ammonia excretion (AE) and ammonia quoti ent (AQ) between the experimental groups (P > 0.05). Mean oxygen consumptio n (OC) was within the range 195.50-211.14 mg O-2/kg/h, and the differences between the groups were statistically significant (P < 0.05). Dietary prote in concentration had no significant effect on the protein concentration of the fish, but dietary fat concentration had a significant influence on the fat concentrations in the fish (P < 0.05), which ranged from 6.6 to 8.5% of pikeperch body wet-weight.