The aim of the current study was to evaluate the effect of dietary supplementation with mango(Mangifera indica) kernel meal (MKM) andoat(Avena sativa) extract (OE) on growth performance, some serum biochemical parameters, immune status and protection of Oreochromis niloticus against Aeromonas hydrophila infections. A total of 180 Oreochromis niloticus fingerlings were divided to three experimental groups (each of 60 and each group was divided into four aquaria, 15 fish/aquarium); The first group was   fed the control diet (without any additive) and the second group was fed diet supplemented with MKM, while the third group was fed diet supplemented with OE for 60 days. Growth performance and immunological parameters (lysozyme, immunoglobulin M) were examined at 2 months of age. Fish were challenged by A. hydrophila and the mortality were recorded after 14 days post-challenge. Fish fed diet contained OE had a higher final body weight, body weight gain and body weight gain percentage when compared with other groups. Immunological parameters estimated in this work were significantly improved (P<0.05) in MKM and OE fed groups when compared with the control group. Survivability after 14 days post-challenge was lower in control group (60%) and higher in other dietary groups. In conclusion, MKM and OE improved the growth performance, blood constituents, immune status and enhanced the challenging ability of Oreochromis niloticus against A. hydrophila.