Impact of feed ration on growth, feed conversion, and variation in body weights of juvenile pike, Esox lucius L., reared in a recirculating aquaculture system

The aim of the study was to determine the impact of different feed rations on growth rate, feed conversion, and variation in body weights in juvenile pike, Esox lucius (L.), cultured in a recirculating system. Three different feed rations were used in the experiment: 0.5% (group L), 0.8% (group O), and 1.1% (group H) of fish biomass. The fish in each group were fitted with Carlin tags and classified according to size as individuals that were small (class S) with a mean body weight of 63.0 g, medium (class M) at 90.7 g, and large (class L) at 137.2 g. After eight weeks of culture, the fish from group O had the highest mean body weight. The final body weight in this group was 7% higher than that in group H and 22.5% higher than that in group L. Differences were also noted among groups with regard to daily (DGR) and specific (SGR) growth rates in body weight and in the protein efficiency ratio (PER). The results indicate that the best culture effects of pike weighing a mean of 100 g and held at a water temperature of 22.5°C were obtained with a daily feed ration of 0.8% of the fish biomass. This ration did not result in increased pike size variation, and it permitted obtaining the greatest increases in body mass in each size group.