EFFECT OF PARTIALLY OR TOTALLY REPLACING FISH-MEAL WITH SOYBEAN-MEAL ON GROWTH OF BLUE CATFISH (ICTALURUS-FURCATUS)

A 12-week feeding trial was conducted in aquaria with juvenile (6 g) blue catfish to examine effects of substituting soybean meal for fish meal in a prepared diet. Four isonitrogenous (34% protein) and isocaloric (2.4 kcal digestible energy/g) diets were formulated to contain 13, 9, 4, and 0% menhaden fish meal (67% crude protein). Soybean meal (44% crude protein) was added in increasing percentages (48, 55, 62, and 69%) to the respective diets. A fifth diet, otherwise identical to the diet containing 0% fish meal and 69% soybean meal, was prepared with soybean meal that had been heated at 105-degrees-C for 60 min prior to diet preparation. After 12 weeks, fish fed a diet with 13% fish meal had a significantly (P < 0.05) higher individual body weight than fish fed any of the other diets. There was no significant difference (P > 0.05) in body weights of fish fed the other four diets. No significant differences (P > 0.05) were found in percentage survival, food conversion ratio, and protein efficiency ratio among diets. Growth of blue catfish was similar to that reported for channel catfish juveniles. However, these data suggest that blue catfish juveniles require at least 13% fish meal in a diet containing 34% crude protein for optimal growth.