This study was conducted to investigate the toxic effects of Ochratoxin A (OTA) on mono-sex Nile tilapia Oreochromis niloticus in a feeding trial for 8 weeks and attempting to detoxify these drastic effects by using some dietary supplements. One percent of each of these supplements (yeast cell wall, and /orNigella sativa) was added to 5mg OTA diet for fingerlings. The OTA contaminated diets significantly (P˂0.05) decreased growth performance (live body weight, body weight gain and relative growth rate) and some tested blood parameters (total protein, albumin, globulin), but uric acid, creatinine and mortality rate were significantly increased by OTA. Either evaluated supplements significantly improved growth performance, blood parameters and mortality rate  which negatively affected by OTA. The best results obtained with yeast cell wall plus Nigella sativa followed by Nigella sativa and yeast cell wall, respectively. The economic efficiency followed the same trend. It may be concluded that the tested supplements have the ability to alleviate the toxicity of OTA and improve the economic efficiency of fish.