The ameliorative effects of Spirulina and Saccharomyces cerevisiae (S. cerevisiae) against fipronil toxicity in Nile tilapia fish were investigated. Fipronil is a kind of pesticide that is widely used in agriculture, thus this trial was conducted to evaluate the effect of fipronil on growth related parameters (final body weight, feed intake, weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio), hematology related parameters (RBCs, WBCs, hemoglobin, packed cell volume, and deferential leukocytic count), biochemistry related parameters (alanine aminotransferase, aspartate aminotransferase, total protein, albumin, urea, and creatinine), histopathology of liver, intestine, gills, and spleen, and gene expression of antioxidants, stress, inflammatory, apoptotic, and related to junction proteins genes as SOD and GPx, COX II, TNF-α, Casp-3, and Claudin-3, respectively, in Nile tilapia (Oreochromis niloticus). Four hundred and five Nile tilapia fish were distributed in a glass aquarium into nine groups according to the Spirulina and S. cerevisiae supplemented diets, with or without fipronil contaminated water. The classified groups are control, Sc: S. cerevisiae (4 g/Kg diet), Sp: Spirulina (1 g/100 g diet), Fb1: 0.0021 mg fipronil/L, ScFb1: S. cerevisiae (4 g/Kg diet) with 0.0021 mg fipronil/L, SpFb1: Spirulina (1 g/100 g diet) with 0.0021 mg fipronil/L, Fb2: 0.0042 mg fipronil/L, ScFb2: S. cerevisiae (4 g/Kg diet) with 0.0042 mg fipronil/L, and SpFb2: Spirulina (1 g/100 g diet) with 0.0042 mg fipronil/L. The results of the present investigation indicated the negative effect of fipronil on the growth performance parameters of Nile tilapia, which was confirmed by the results of hematology, biochemistry, and histopathology. In addition, the results of gene expression of antioxidants, stress, inflammatory, and apoptotic genes indicate the genotoxicity of fipronil. However, these negative effects were ameliorated by Spirulina and Saccharomyces dietary supplementation.