ABSTRACT
Lake Manzala, the most important and largest brackish water lake in Egypt, suffers from water pollution induced by agricultural drainage, industrial wastes, sewage, and invasion of Mediterranean Sea water. Besides, high temperature plays a great role for appearance of some temperature dependent bacterial disease such as emphysematous putrefactive disease [EPD] or what is called Edwardsiella septicaemia. Catfish [Clarias lazera] showing the characteristic pathognomonic signs and lesions of EPD were subjected to organoleptic examination, clinical, postmortem and bacteriological examination. The bacterial isolates [11%] were morphologically and biochemically related to Edwardsiella tarda. Reisolation of E. tarda was recovered after the experimental infection of the healthy Clarias lazera by intraperitoneal and intramuscular routes revealing the same clinical signs and lesions. After using drug sensitivity tests, E. tarda was highly sensitive to oxytetracycline, chloramphenicol and kanamycin. The organoleptic examination and measurement of pH revealed the unpleasant and nauseating characters of catfish Clarias lazera infected with EPD either naturally or experimentally which was absolutely unfit for human consumption