Studies on Vibriosis among Some Marine Fishes in Lake Temsah

During the current study, a total of 160 marine fishes of two different species represented as: seabass (Dicentrarchus labrax) and Tilapia zillii randomly collected from Lake Temsah at Ismailia governorate from August 2015 to July 2016. Seventy-six of fishes found to be infected with both V. anguillarum and V. parahemolyticus, as Gram negative, short rod bacilli as comma shaped and motile bacteria. D. labrax was the most infected fish spp 41 %, pursued by Tilapia zillii 35 %. The highest prevalence of vibriosis among naturally infected marine fishes was recorded during summer 67.5 %, pursued by spring 55 %, then autumn 40 %, while the minimal prevalence 27.5 % was registered during winter. Molecular investigation of pure isolates using sets of both universal and specific primers gave PCR products with clear band of 120 and 519 bp lengths, respectively. Experimentally infected fish subjected to a dose (107) of V. anguillarum presented higher morbidity and mortality rate up to 80 %. Most of infected fish showed skin ulceration in the ocular side, others displayed redness and scattered hemorrhagic spots on the abdomen with fin erosion. The histopathology of naturally infected marine fishes exhibited severe inflammatory reactions manifested by leukocytes infiltration with activation of melanomacrophage centers as well as tissue necrosis.