Abstract: This experiment was conducted to study the effects of dietary chromium picolinate (Cr-Pic) on growth performance, carcass composition and internal organs indices of mono-sex Nile tilapia (Oreochromis niloticus) fingerlings in an in-door 12-weeks trial. Fish with similar body weight (28.00±0.96 g) were distributed randomly into seven treatments at the same stocking density of 20 fish m-3, being the control fish group (T1) which was fed a basal diet free from supplemented Cr-Pic. Other fish groups were fed the basal diet supplemented with graded levels of Cr-Pic, being 200 ppb (T2), 400 ppb (T3), 600 ppb (T4), 800 ppb (T5), 1000 ppb (T6) and 1200 ppb (T7). The obtained results revealed that the dietary graded levels of Cr-Pic had no significant (p≥0.05) effects on growth performance, carcass composition and internal organs' indices of the experimental fish, but dietary Cr-Pic at 400 ppb (T3) led to significant (p≤0.05) increase in dry matter and crude protein of fish carcass compared with the control treatment and also the same treatment (T3) had significant increased of gonado-somatic index (GSI ♂, %) among all treatments.