Five experimental diets were formulated to contain various percentages of black seed cake (BSC) as a partial replacement for soybean meal (SBM). The substitution levels were 0 (control), 10, 30, 50, and 70% of crude protein of BSC that replaced the same percentages of crude protein from soybean meal. All diets were isonitrogenous (35% crude protein) and isocaloric (477.49 Kcal/100 g diet) and protein energy ratio ranged from 72.90 to 74.34 mg protein/Kcal gross energy. Nile tilapia (Oreochromis niloticus) fingerlings were randomly distributed at stocking density of 20 fish per aquarium. The average initial weight offish ranged from 16.0 to 17.5 g/fish. Each three aquaria (represented three replicates) of one treatment were fed on one of the experimental diets. Diets were given to fish at a rate of 3% of live body weight for 90 day. The daily feed was offered twice daily.The obtained results revealed that the highest final weight, weight gain and SGR were recorded in fish group reared on diet 10% BSC 35.48, 16.09 (g/fish) and 0.81 (%/day) respectively, while the lowest values were recorded in fish group fed control 33.21, 16.09 (g/fish) and 0.47 (%/day) respectively. No significant differences in SGR, FCR, feed intake, survival rate and hepatosomatic index were observed among different treatments.Results of DM, CP and ash in fish body composition did not show any significant differences under all treatments. Differences were significant in crude fat (P<0.05) among fish groups fed 70% BSC and either fed control or 50% BSC.Concerning nutrients digestibility, results showed that crude protein and gross energy values under BSC diets were lower than those in control. The values of apparent protein digestibility, apparent carbohydrate digestibility and apparent gross energy digestibility were higher in fish groups fed BSC diets than that of the control group.