The effects of replacing fishmeal with squash (Cucurbita maxima) seed meal (SSM) on Oreochromis niloticus juveniles were investigated on a 30-day feeding trial. Triplicate groups of ten (10) O. niloticus juveniles (2.54±0.949 g) stocked in polyethylene tanks received iso-nitrogenous diets with SSM inclusion levels of 0%, 5%, 10%, 15% and 20%. Fish fed 5% SSM inclusion level showed the highest average weight gain (202.25±36.26%) and specific growth rate (3.76±0.42%) among the fish fed SSM-containing diets. However, there were no significant differences between the average weight gain and specific growth rate of fish in all diets. Fish fed S5, S15 and S20 showed significantly higher protein carcass levels; lipid levels were not significantly different while hepatosomatic index in fish fed S20 was significantly higher than fish fed other diets. Cost analysis of diets revealed S5 as the most cost-effective diet. SSM diets were comparable to the positive control diet as these were efficiently utilized by the fish, thereby making it a potential candidate ingredient/replacement for fishmeal.