The dietary effects of Lemon grass (Cymbopogon citratus) leaf powder meal on growth performance and immune response of African catfish (Clarias gariepinus ) was evaluated. 40% crude protein (CP) diets supplemented with 0.0g (D1), 0.5g (D2), 1.0g (D3), 1.5g (D4) and 2.0g (D5) of C. citratus leaf powder were prepared and fed to C. gariepinus fingerling s (mean weight 7.30 ±0.02g) for eight weeks. 15 C. gariepinus fingerlings were randomly distributed into 15 plastic tanks each representing five treatments in triplicates. Feeding was done twice daily. After the feeding trial, fish from each treatment group were challenged with pathogenic Aeromonas salmonicida, through intraperitoneal (I/P) injection and observed for 14 days for abnormal clinical signs and mortality. There was a significant difference (p>0.05) in the mean weight gain, and specific growth rate of fish fed diets with different inclusion levels of C. citratus leaf powder. There were significant differences (p>0.05) in white blood cells among treatments. At the inclusion level of 2.0gkg-1 of C. citratus , the best immunity against A. salmonicida was recorded. The result of this study has shown that C. citratus can be incorporated into fish feed to replace synthetic antibiotics for sustainable aquaculture.