Insect meals have been proposed as a potential alternative protein source for replacing fishmeal (FM), the key ingredient in aquaculture diets, yet is the most scarce and expensive. However, not much work has been done on the effects of replacing FM with black soldier fly (Hermetia illucens ) larvae meal (BSFLM) on the growth and economic performance of African catfish (Clarias gariepinus) fingerlings. This study investigated the effect of replacing FM with BSFLM on the growth and economic performance of African catfish. Five isonitrogenous (40% CP) diets were formulated to replace 100% FM, 75% FM, 50% FM, 25% FM and 0% FM with BSFLM, hereafter referred to as BSFLM0, BSFLM25, BSFLM50, BSFLM75and BSFLM100 diets, respectively. Six hundred mixed-sex fingerlings of mean weight 0.46±0.02g were stocked in 15 plastic tanks (40 fingerlings/tank, three replicates/treatment). Fish were hand-fed at 6% body weight twice a day for 12 weeks. Significant differences (P<0.05) were found in final body weight, body weight gain, specific growth rate, feed conversion ratio, and condition factor.The best growth performance was recorded in fish fed on BSFLM25. The economic analysis indicated that BSFLM diets reduced significantly (P<0.05) the incidence cost compared to the (BSFLM0). BSFLM0 had the highest incidence cost (KES 99.99), while BSFLM100 (KES 59.93) yielded the lowest. BSFLM diets significantly increased (P<0.05) the profit index compared to BSFLM0. BSFLM100 and BSFLM25 had the highest profit indexes (KES 5.06) and (KES 4.28) respectively. Additionally, the best harvest weight and value of fish were found to be higher in BSFLM25 compared to other compositions, even when the amounts fed and feed cost per kg were not significantly different from BSFLM0. The study demonstrated that BSFLM is a cost-effective alternative to FM in diets of African catfish and hence can replace BSFLM up to 25% without negative effects on growth and economic benefits.