The depletion of fish stocks in Lake Victoria is putting severe strain on fish supplies for human consumption and aquaculture feed formulation. Due to the fish stocks high demand and limited supply, fishmeal prices are rising, increasing the cost of feed for aquaculture. As a result, up to 70% of variable aquaculture expenditures are related to feed. Alternative feed sources, such as insect meals, have been heavily advocated for in light of the limited supply of fishmeal. This study replaced fish meal (FM) with black soldier fly larvae (BSF) meal (in Oreochromis niloticus diet, with replacement levels ranging from FM 0%, BSF 2 25%, BSF 3 50%, BSF 4 75% and BSF 5 100%). The feeding trial lasted 84 days and evaluated the effect of replacing BSF on fish's growth performance. Results indicate that all the fish accepted the experimental diets well. Regression on categorical variables analyses on growth performance revealed a significant relationship between the variables for length and weight respectively. For log length F (5, 99) = 628.02, P<0.05, with an R 2 of 0.96 and log weight (5, 99) = 977.61., P<0.05 with an R 2 of 0.97. In terms of economic analysis, O. niloticus fed with increasing levels of H. illucens was more profitable at replacement levels of 50, 75 and 100%. Based on these findings replacing fishmeal with Hermetia illucens by up to 50% is more cost effective for aquaculture production and can effectively contribute to higher yields and optimal O. niloticus growth performance.