Mahmoud Aly Mahmoud

Some fish species are suffering from continuous depletion due to devastating environmental changes at their native aquatic environment. Qarun Lake and Suez Gulf are among the most vulnerable areas. Thus, representative fish samples from those areas were inspected for the presence of any fish pathogenic bacteria. The inspected samples included six different species; Epinephelus tuvina, Siganus rivulatus, and Dedlechilus labiosus native to Suez Gulf at Suez governorate; Tilapia zilli, Mugil capito and Solea vulgaris native to Qarun Lake at El- Fayoum governorate. A total of 600 samples were examined throughout the different year seasons. Gram positive and negative fish pathogenic bacteria were isolated from a total of 245 fish sample. Among those samples, the following bacteria were retrieved in the following percentages respectively, 17.55% (V. anguillarum), 16.73% (V. alginolyticus), 15.51% (P. piscicida), 15.91% (Ps. fluorescens), 13.46% (S. fecalis), 11.02% (A. hydrophila), 6.12% (A. sobria) and 3.67% were infected with Staph. aureus. The Siganus rivulatus was the highest infected fish species with a prevalence of 8.33%, while Mugil capito was the lowest infected species (5.67 %). The highest total prevalence of bacterial infection was recorded in summer season (40.81%) while the lowest was recorded in winter (15.91%). The aforementioned bacterial isolates were successfully re-isolated from experimentally infected fish. The retrieved isolates were matched against standard isolates as well as confirmed to be positive using semi- automated (API 20 E) and conventional biochemical tests.