The current study determined the influences of supplementing Nile tilapia (Oreochromis niloticus) basal diet with a prebiotic mixture on hematological, immune and biochemical parameters and growth performance. Two fish groups (Average weight 16.0 ± 0.5 g) were supplemented with prebiotic Fermos® at a rate of 0.5 and 1.0 g/kg diet and the third group which served as control received basal non-supplemented diet. The feeding trial continued for 6-weeks; and representative blood, serum as well as liver samples were collected from the three groups at the end of the third and sixth week. Differences in hematologic parameters, serum biochemical and oxidative indicators were determined. Results showed that Fermos® showed significant increase in hematological markers (mean corpuscular hemoglobin, packed cell volume concentrations, total leukocytic count, monocytes, and lymphocytes); and a significant decrease in (mean corpuscular hemoglobin concentration, eosinophils and basophils counts). Fermos® increased serum albumin, globulin, and total protein. Biochemical parameters (AST and ALT levels) showed significant decrease at the end of the sixth week and third week, respectively in Fermos® groups, while glucose levels were significantly increased at the two sampling points for supplemented fish. All immune, antioxidants and growth parameters were improved in supplemented fish, compared to control group. Conceivably, our results demonstrated the beneficial effects of supplementing O. niloticus with Fermos® prebiotic on hematological parameters, immune and biochemical and growth profiles.