Dietary protein requirement of juvenile tiger puffer (Takifugu rubripes)

This study was conducted to determine the optimum dietary protein requirement for the growth of juvenile (initial weight, 17.05 ± 0.17 g) tiger puffer. Five semi-purified diets were formulated with casein to contain graded levels of protein levels of 35, 40, 45, 50 and 55%. Each diet was fed to triplicate groups of the fish in a flow-through system for 8 weeks. After the 8-week feeding trial, growth of fish fed the 40% diet was not significantly different from that of fish fed 45, 50 or 55% dietary protein, but significantly higher than that of fish fed the 35% diet. The lowest feed efficiency was found in fish groups fed 35% diet. Protein efficiency ratio of fish fed the 45, 50 and 55% diets was significantly lower than that of fish fed the 35 and 40% diets. No significant differences were observed in feed intake and survival among all the fish groups. Serum aspartate aminotransferase activity of fish fed the 45% diet was significantly lower than that of fish fed the 35% diet, but was not significantly different from that of fish fed the 40, 50 and 55% diets. Whole body protein content of fish fed the 50 and 55% diets was significantly higher than that of fish fed the 35% diet, but was not significantly different from that of fish fed the 40 and 45% diets. This result indicates that juvenile tiger puffer requires approximately 41% dietary protein for optimum growth and physiological performances.