This study determined the level of fermented soybean meal (FSM) that could be substituted for fish meal in the diet for parrot fish Oplegnathus fasciatus. Fish meal (FM) was used the sole protein source in the control diet. FSM was substituted for 20, 40, 60, 80, and 100% of the fish meal in the experimental diets. The FSM resulted in increased crude protein, crude fat, and crude ash, but decreased crude fiber. The methionine and tryptophan contents in the FSM increased, while lysine and threonine decreased. The 18:2n-6 fatty acid content decreased from 55.30% to 28.67%. Fermentation increased 20:5n-3 (EPA) and 22:6n-3 (DHA) by 2.03% and 15.54%, respectively, although the differences were not significant. Based on growth performance, we concluded that FSM could replace up to 60% of FM for the maximum growth of juvenile parrot fish.