The aim of this study was to investigate the modulation effects of thyme and fenugreek as food additives on sharptooth catfish immunity. Three diet regimes, a basic (control); Thyme diet (1%) and fenugreek diet (1%) were formulated and used to feed fish for 30 successive days. Half of the fish were used to investigate some of the immune parameters as differential leucocytic counts, serum globulins, phagocytic activities, phagocytic index, catalase and glutathione peroxidase. The other half of fish was subjected to challenge infection with Aeromonas hydrophila to investigate the disease resistance ability of the fish received the feeding additives. The results showed that, the serum globulins have significantly increased in fish fed with fenugreek, while the total serum protein has significantly increased in fish fed with thyme or fenugreek. Glutathione peroxidase (Gper) and catalase (CAT) increased significantly in the groups fed on fenugreek or thyme diets when compared to the control group. Phagocytic percent and index of fish fed on fenugreek were significantly higher than those of the control and thyme groups. Monocytes were significantly increased in all treated groups, while lymphocytes were significantly decreased in all treated groups. Weight gain of C. gariepinus was significantly lower in the group fed on thyme than in the control group, while it was insignificantly higher in fish fed fenugreek. After 30 days of feeding, fish were challenged with A. hydrophila, the cumulative mortalities were 40% and 26.67 % in fish fed on  diet supplemented with 1% thyme and fenugreek, respectively, compared to 66.7% in the control group. It was concluded that thyme and fenugreek are be able to positively stimulate the immune system of C. gariepinus and decrease mortality rate in fish challenged with A. hydrophila.