A 12-week feeding trial was undertaken to evaluate the effect replacing of fish meal with fermented fish by-product silage (FBS) as feed ingredient for Nile tilapia, Oreochromis niloticus fry. Five isonitrogenous (300 g CP kg-1 dry matter, DM) and isocaloric (19 MJ gross energy kg-1 DM) diets were formulated and FM was replaced by FBS in five increased levels, 0, 25, 50, 75 and 100% g to formulate the five experimental diets, FBS0, FBS25, FBS50, FBS75 and FBS100, respectively. 375 O. niloticus fry (1.72±0.05g) were randomly divided into five groups (each group having three replicates) and fed for 84 days were randomly distributed into 15 glass aquaria (160 liter), and each aquarium holding 25 fish and randomly assigned to one of three replicates of the diets. Replacing levels of FM with FBS up to 50% did not significantly (P