The present experiment was conducted to evaluate the effect of acidifiers on growth performance and immunity of the African catfish C. gariepinus. This experiment was carried out in the wet lab of Fish Production Branch, Department of Animal Production, Faculty of Agriculture, Ain Shams University. A total of 120 fish were selected as healthy catfish which had a uniform size and average weight of 94.93 ± 0.89 g. A thirty of catfish were used in each treatment divided into three replicates as (10 fish/ quadrate tank). Four experimental diets were formulated at 35 % crude protein with different levels of organic acid blend (OAB); diet was supplemented with 0, 2, 4 and 6 ml of organic acid per kilogram diet. Growth parameters, apparent digestibility of crude protein and ether extract were measured. The chemical proximate analysis for whole-body of fish was conducted at the end of the experimental period. Hematological parameters of fish and liver function enzymes were also measured. The fish group fed on 0.6 % organic acids blend showed the highest significance (P < 0.05) increase in total weight gain (438 ± 14.24 g), specific growth rate, best feed conversion ratio, feed efficiency ratio and highest protein efficiency than the rest of experimental groups. The highest apparent digestibility for crude protein were achieved in the third fish group which fed diet supplemented with acidifiers at 4 ml / kg diet and have significant difference (P < 0.05) with other groups. Data obtained in hepatosomatic index % showed no significant difference among different treatment refers to the health status of liver. However, ALAT 
and ASAT recorded high values in the higher group of OAB-treated fish indicating that liver could be affected. Hematological parameters were in normal range except for PCV, Hb, RBCs, and WBCs count which were decreased in the high dose of treated fish. Finally, it could be concluded that using of acidifiers as feed additives at lower doses can enhance growth, productivity and immunity of the African catfish (C. gariepinus).