An 8-week feeding trial was conducted to evaluate the effects of crystalline and capsulated DL-methionine on fish meal replacement with soybean meal in diets for Japanese seabass Lateolabrax japonicus.A reference diet(control)was formulated to contain 40% fish meal.A 2×4 layout was used, including two fish meal replacement levels(40% or 80% of the fish meal in control diet were replaced with soybean meal)and four types of DL-Met supplementation(A:Crystalline DL-Met;B:Capsulated DL-Met;C:Crystalline DL-Met + capsule material;D:a premix containing B and C at 1:1).The 8 test diets were formulated isonitrogenous and isolipidic.0.5% A, 1.3% B, 1.3% C or 1.3% D were added in diets LA, LB, LC and LD(dietary fish meal level was 24%), respectively, while 0.7% A, 1.8% B, 1.8% C or 1.8% D were added in diets HA, HB, HC and HD(dietary fish meal level was 8%).Initial body weight of Japanese seabass was(6.0±0.1)g.Fish meal replacement level significantly affected weight gain(WG), feed intake(FI), feed conversion ratio(FCR), nitrogen retention efficiency(NRE), total nitrogen wastes output(TNW), hepatosomatic index(HSI)and proximate composition of whole fish(P<0.05);while types of DL-Met affected total phosphorus wastes output(TPW)(P<0.05).The WG and NRE decreased(P<0.05), while the FCR and TNW increased, with increasing of fish meal replacement level, whether crystalline or capsulated DL-Met was added.At the same fish meal replacement level, no significant differences were found in the WG, FCR, NRE, CF, HSI, body composition, TNW and TPW between fish fed the diets with supplementation of A, B, C or D(P>0.05).This study indicates that dietary fish meal level for Japanese seabass can be reduced to 24% when SBM was used as a fish meal substitute, and supplentation of crystalline or capsulated DL-Met could not enhance fish meal replacement level by SBM in diets for Japanese seabass.