The present study was carried out at the World Fish Abbassa Sharkia, Egypt with cooperation of Animal Production Research Institute (APRI) Agriculture Research Center Giza, Egypt. The study was conducted to investigate the possibility of incorporating by-products of mushroom growing on rice straw as an energy source and cheap alternative feed stuffs instead of the diets in all-male Nile tilapia, O. niloticus fingerlings Abbassa strain (G9) (6.03g±0.22g) were obtained from the World Fish. Genetic improvement program. Five experimental diets were formulated, as iso nitrogenous (30.80 % CP) and isocaloric (4325.94 Kcal/kg diet), containing 0, 5, 10, 15 and 20% of mushroom by-product T1, T2, T3,T4 and T5, respectively and fed to monosex Nile tilapia, (Oreochrom isniloticus) fingerlings with average individual weight of (6.03g ± 0.12g).Total of Fish were fed at a rate of 5 % of total biomass, tilapia were hand-fed to apparent satiation which was divided between three feeding times daily (8:00, 12:00, and 15:00 hours). The results showed no significant differences between all treatments (P>0.05) in growth performance and feed protein utilization of fish up to 20% compared with the control in Nile tilapia fingerlings diets resulted a better economic efficiency.