Replacement of dietary fish meal by soybean meal supplemented with crystalline methionine for Japanese seabass (Lateolabrax japonicus)

Two 8-week feeding trials were conducted to evaluate soybean meal (SBM) as a fish meal substitute in diets for Japanese seabass, Lateolabrax japonicas. In trial I, a control diet (C) contained 400 g kg^-1 fish meal, and 20%, 40%, 60% and 80% of the fish meal were replaced with SBM, supplied with 3 g kg^-1 DL-methionine and 2 g kg^-1 L-lysine (S20, S40, S60 and S80). In trial II, 60% and 80% of the fish meal in diet C were replaced with SBM, supplied with DL-methionine at 3 g kg^-1 (S60, S80) or 6 to 7 g kg^-1 (RS60, RS80). The feed intake was lower in fish fed diet C than in fish fed diets S20, S40, S60 and S80 (trial I). No significant differences were found in the weight gain, nitrogen retention efficiency and body composition between fish fed diets C, S20, S40 and S60 (trial I), between fish fed diets S60 and RS60 or between fish fed diets S80 and RS80 (trial II). This study indicates that dietary fish meal level for Japanese seabass can be reduced to 160 g kg^-1 by using SBM as a fish meal substitute.