Effects of Supplementation of Dietary Bamboo Charcoal on Growth Performance and Body Composition of Juvenile Japanese Flounder, Paralichthys olivaceus

A 50-d feeding trial was conducted to determine the effect of dietary bamboo charcoal (BC) on growth performance, body composition, and ammonia nitrogen excretion of juvenile Japanese flounder, Paralichthys olivaceus. Six levels of BC (0, 0.25, 0.5, 1, 2, and 4%) were supplemented to the basal diet composition and fed to fish (initial body weight [BW], 3 +/- 0.1 g). At the end of the trial, fish were used for the determination of apparent digestibility of dry matter and protein, and cumulative ammonia nitrogen excretion rates. Weight gain, specific growth rate, feed efficiency ratio, and protein efficiency ratios of fish fed 0.5% BC diet were significantly (P < 0.05) higher than those of fish fed the control diet (without BC). Moreover, apparent digestibility of dry matter and protein of fish fed BC diets were significantly (P < 0.05) higher than those of fish fed the control diet. Cumulative ammonia nitrogen excretion over a subsequent 12-h period decreased with increasing dietary BC. In conclusion, the diet supplemented with 0.5% BC was found to have a suitable level to fulfill the maximum growth performance and to decrease the ammonia nitrogen excretion of flounder, under the conditions applied in this study.