Abstract: Background and Objective: Reducing fishmeal levels is key to reducing feed costs for commercial fish farming and ensuring the sustainability of this enterprise. This study was aimed to evaluate the effects of replacing fish meal protein with locust meal protein in the feeds for fingerling Oreochromis niloticus (3.5±0.94 g). Materials and Methods: Seven practical diets (350 g kg–1 crude protein, 14.90 kJ g–1 gross energy) replacing 0, 10, 20, 30,40, 50 and 60% fish meal protein by locust meal protein were prepared. The diets were fed to triplicate groups of fish near to satiation for 8 weeks. Results: The live weight gain (LWG, 262.6-719.7%), feed conversion ratio (1.58-3.18), protein efficiency ratio (0.70-1.41), specific growth rate (2.30-3.76% day–1), protein retention efficiency (3.62-9.42), hemoglobin (61.2-98.1 g dL–1), hematocrit (16.37-31.35%) and RBCs counts (13.5-23.2×106 mm–3) in fish fed diets with 0, 10,20 and 30% replacement of fish meal with locust meal did not show any significant differences. Conclusion: However, further replacement of fish meal by locust meal beyond 30% resulted in a significant fall (p<0.05) in the above parameters indicating that fish meal could be replaced by locust meal up to 30%. Based on the broken-line analysis of LWG, the optimum replacement level was found to be 29.8% which would be useful in formulating cost-effective commercial feeds for the intensive culture of this fish.