An experiment was carried out to determine the optimum protein to energy ratio for maximum growth, diet utilization and body composition of juvenile Nile tilapia (Qreochromis niloticus) (3,6g initial body weight) raised in glass aquaria. A 4 x 2 factorial design was employed in which eight diets containing 12, 16, 20 or 24% protein each with 245 or 262 kcal metabolizable energy (ME)/I00g were used. Each treatment was replicated in three glass aquaria. Results revealed that. increasing dietary crude protein increased final body weight (FBW) significantly (P < 0.05). Fish that maintained at 20 or 24% protein levels exhibited significantly the greater mean FBW compared to that fed 12% protein. Also, increasing dietary energy significantly (P < 0.05) increased FBW. Interaction between dietary protein and energy indicated that the 20 % protein level with 245 kcal ME/lOOg (81.6 mg P /kcal ME) showed the best P/E ratio for growth and feed utilization. The results also showed that feed intake increased as dietary protein increased, however dietary energy seemed to have no influence on this trait. Feed conversion ratio (FCR) was improved as protein increased to 20%. Moreover, no further significant improvements in either FBW or feed utilization were observed as protein and energy increased beyond 20% protein and 245 kcal/lOOg ME. Body protein was increased with increasing dietary protein, while body Jipid and moisture were not affected. On the other hand, increasing dietary energy significantly (P < 0.05) increased lipid contents of the fish body and decreased body moisture but did not affect body protein. Protein efficiency ratio (PER) and protein productive value (PPV) were decreased as dietary protein and energy increased, while energy retention (ER) increased. Based on wreight gain, feed efficiency and body composition data, it could be suggested that 20% dietary crude protein level with 245 kcal/lOOg ME are optimum for Nile tiJapia in glass aquaria, using commercial ingredients.