This study was cared out to investigate more information about the prevalence of Motile Aeromonas Septicacmia (MAS) in both cultured and wild Nile tlapia and Karmout catfish. The clinical signs and P.M. lesions were pronounced in cultured fishes. Aeromonas hydrophila was recovered from all MAS affected fishes. The incidence of MAS in cultured and wild Nile tilapia was 10.0% and 2.5% respectively while it was 18.75% and 6.25% in cultured and wild Karmout catfish respectively. Reisolation of A. hydrophila was recovered after experimental infection of Karmout catfish by I/P and S/S revealing the same clinical signs and lesions. The histopathological pictures produced by such microorganisms along the course of experimental infection were discussed. Besides, A. hydrophila isolated from cultured fishes were more resistant to antibiotic sensitivity test than those isoulted from wild fishes.