Neuropeptide Y (NPY) is a 36 amino acid peptide with a direct action on food intake and growth. This study assessed the effect of NPY administration by immersion on growth of Clarias gariepinus fry. The results of the experiment showed that the weight increase in the NPY group was 87% and 64% greater than the weight in the control group after 18 and 30days, respectively. The length increase in the NPY group was 27% and 16% greater than in the control group at days 18 and 30. In recent years, it has become increasingly apparent that the immune and neuroendocrine systems are close linked. Therefore, the actions of this peptide on antioxidant defenses (superoxide dismutase, catalase and reduced glutathione) and innate immunity (lysozyme, lectins and nitric oxide) have also been explored in this research. The results have showed that the administration of recombinant tilapia NPY by immersion induced a specific increase in reduced glutathione concentration and superoxide dismutase activity.