A 42-day experiment was performed to evaluate the growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) fingerlings fed iso-lipidic diets (5% lipid) contain 17% or 25% of cassava starch extract from fresh root (R starch) or from dry chips (D-starch) at 37% and 30% protein levels. The diets were ie: 37% protein -FM25R17 & FM25D17, 30% Protein- FM15R25 & FM15D25. 144 fish (1.11+0.02g) were distributed in 12 tanks (54 L). Protein level or starch source had no impact on final weight, length, average daily gain, specific growth rate, food conversion ratio, hepato somatic index, viscero somatic index, and Whole-body composition of fish. Protein Efficiency Ratio was not affected by starch source; however, it was significantly higher in diets with low protein content. Apparent Digestibility Coefficient of dry matter was not affected by starch source but was significantly high in low (30%) protein diet. Inclusion of R starch substantially reduced the cost of feed and increased economic profitability. Tilapia fed FM15R25 diet showed similar growth and nutrient utilization to fish fed 37% protein diets and cost of FM15R25 diet was lower than other diets. Therefore, FM15R25 is the best practical diet among the tested diets for Nile tilapia fingerlings.