The aim of the study was to determine what impact feeding juvenile common whitefish, Coregonus lavaretus (L.), different feed rations had on rearing indexes and oxygen consumption during culture in recirculation systems. Three feeding treatments were applied: 2% (group L), 3% (group M), 4% (group H) of fish biomass. The final juvenile common whitefish weight increased with increasing daily feed rations. Fish from group H (largest feed ration) had statistically significantly (P < 0.05) higher body weights (50.3 g) and higher feed conversion ratios (1.14) than did the fish in the other two groups. However, the lowest oxygen consumption (192.9 mg O2 kg-1 h-1) was noted in group L (smallest feed ration). The results of the experiment indicated that the size of the daily feed ration has a significant impact on the rearing results and oxygen requirements of juvenile common whitefish. The optimum daily feed ration for juvenile whitefish weighing 10-45 g and at a water temperature of 18.0°C is 3% of the stocking density.
