An 8-week growth trial was conducted to evaluate the effects of an animal protein blend(APB)with poultry byproduct meal,meat and bone meal(beef),spray dried blood meal,and hydrolyzed feather meal at the ratio of 40∶35∶20∶5 to replace low temperature steam-dried fish meal with or without supplementations of lysine,methionine and threonine in diet of juvenile Japanese sea bass, Lateolabrax japonicus,on growth performance and body composition.Three replacing levels were designed at 50%,75% and 100%,respectively.Growth performance of fish was reduced with higher APB inclusion levels; Fish fed control diet showed significantly higher survival feeding rate(FR),specific growth rate(SGR)and protein efficiency ratio(PER)than those fed diets containing levels of APB; Supplementation of crystallized amino acids(CAA)enhanced the feeding rate and growth performance and reduced hepatosomatic index and increased whole body crude protein,crude lipid and gross energy.Interactions of CAA supplementation and fishmeal replacing levels on growth performance and body composition were significant.Results demonstrate that 1) no more than 50% of LT-FM can be replaced by APB in diet of juvenile Japanese sea bass; 2) supplementations of CAA could improve potential of APB replacing dietary fish meals; 3) crystallized amino acids can be relatively efficiently utilized by Japanese sea bass.