This study was carried out to explore the effect of partial substitution of dietary fish meal by differently processed soybean meals on the growth and physiological reponses of juvenile Japanese sea bass Lateolabrax japonicus. Six diets were formulated to be isolipidic (13% lipid) and isonitrogenous (41% crude protein). A fish meal based diet was used as the control. The treatments consisted replacing 50% dietary fish meal protein by defatted soybean meal, soy protein concentrate, soy protein isolate, fermented soybean meal and a product of soybean-fish meal co-cultured fermentation, respectively. Each experimental diet was fed to 3 replicate groups of 10 fish (initial body weight of 7.6 g) two times daily to apparent satiation for 10 weeks. At the end of the growth trial, the final weight, percent weight gain and feed utilization was highest in the control fish. The growth of fish fed diets with soy protein concentrate or soybean-fish meal co-cultured were superior to that of fish fed diets with defatted soybean meal or fermented soybean meal. On the other hand, biological measurements and hematocrit value were significantly affected by dietary treatments.Keywords: Japanese sea bass, soybean meal, diet, growth