---

In this study, changes on biochemical and immune parameters of Oscar fish, Astronotus ocellatus under the influence of garlic extract has been studied. A total of 300 Oscar (initial weight 8/37 ± 0/36 g) were distributed in four treatments and each treatment was diet with garlic extract supplement, (0.0%, 0.5%, 1.5% and 2.5%). Period test was 8 weeks. The samples were taken and biochemical parameters such as total protein, albumin, globulin, triglycerides, cholesterol, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) and immune parameters such as C3, C4 and lysozyme activity were measured by standard methods. Total protein and albumin increased in fish fed with the extracts of garlic 1.5%, but no significant difference was observed in globulin in four treatments. Triglycerides, cholesterol, ALP and AST in all treatments fed garlic extract were decreased. Safety parameters include C3 and C4 treated in samples with the extracts of garlic 1.5% and lysozyme activity increased in all treatments. The results of this study showed that garlic extract has positive effects on biochemical and immune indicators in Oscar fish and the best observed was in the treatment with 1.5%  garlic extract.