The present study was carried out to evaluate the effect of adding ascorbic acid to Tilapia fish diets on survival, growth, physiological parameters and total production. O. niloticus at average initial body weight 20.3+0.9g and length
13.5+0.6cm, were stocked in concrete ponds at a rate of 5 fish/ m3, and offered a diet of 5% of body weight, six days weekly , twice daily . The basal diet contained 30% crude protein divided into five tested diets. Ascorbic acid was
added to the basal diet at different levels, 0 , 300, 600, 900 and 1200 mg AA /kgdiet.The results show that tilapia growth performance indices (FBW, A.DG,SGR, GR and FCR) were increased with increasing ascorbic acid (AA) levels.
Diet contained 900mg/kg recorded the best value, compared to the control diet.recorded from diet (4) compared to the control diet. Survival and production were increased with the increase of ascorbic acid level until 900mg/kg diet
which recorded the best results.Similar results were obtained in blood properties (Erythrocyte,hematocrit and hemoglobin) as values showed the same pattern;, fish groups offered diet contained 900mg AA/kg had the best results comparing to the control diet; muscles, serum lipid values decreased with increasing A.A level.
Protein content showed best values in fish fed A A up to 900mg/kg diet.The observation on fish growth and health showed that Ascorbic Acid  can be used as a commercial compound to reduce production costs and to
increase total final profit.