To evaluate the effect of Spirulina platensis inclusion in diets for Nile tilapia fingerlings, a completely randomized experimental design was developed with 4 treatments and three replicates. Diets with 4 inclusion levels (control diet (Sp0), 0.5% (Sp0.5), 1% (Sp1) and 1.5% (Sp1.5)) were prepared. 180 Nile tilapia fingerlings with average initial weight of 8.46±0.17 g were assigned to twelve experimental tanks. The experiment lasted for ten weeks. At the end of the experiment; growth

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... e, the whole body composition was determined and serum samples for lysozyme, IgG, IgM values and catalase activity were collected and antioxidant status of Nile tilapia muscle were determined. The results showed that group supplemented with 1% S. Platensis have higher body weight and lower FCR than the control group and other groups. S. platensis inclusion increased activity of glutathione reductase, and reduce MDA formation. Levels of lysozyme, IgG and catalase activity were higher in S. platensis supplemented groups but don't have significant effect on IgM level. In conclusion, Spirulina platensis supplementation increased antioxidant protective capacities. It also affected some innate and humoral immunity parameters as well as don't have negative effect on fish growth.