The influence of food protein levels on the hematological parameters and zootechnical indices of juveniles of Osteoglossum bicirrhosum “arahuana” grown in floating cages for 90 days at the IIAP facilities was determined. A total of 60 Arahuana juveniles with initial weight and length of 74.19 ± 0.13 g and 26.43 ± 1.31 cm were randomly distributed in ten cages (6 fish / cage), which were fed three diets containing 28%, 40% and 50% crude protein (CP) and a control with forage fish (Cichlasoma sp. 49.6% CP), using a feeding rate of 6% of the total biomass with a frequency of 2 times a day (8:00 and 16:00 hours). Growth indices (0, 23, 45, 70 and 90 days) and hematological parameters (0, 45 and 90 days) were evaluated. The results show that the diet of 50% CP and control (49.6%) obtain better significant results (p <0.05) in weight (174.58 ± 48.78 g and 172.58 ± 26.89 g) and length (...