The main objectives of this work: 1-      Seasonally collect fish from the Mediterranean Sea and study the clinical picture of the examined fish. 2-      Isolation and identification of the pathogenic bacteria affecting Solea fish. 3-      Registering the percentage of total and seasonal prevalence in such fish. 4-      Make trials for diagnosis using recent techniques. 5-      Application of biosafety in the lab. 6-      Commitment to the basis and principles of scientific research ethics in all study stages. 7- Studying histopathological changes caused by these bacterial diseases from naturally infected fish. In the present study, a total of 120 Egyptian soles (Solea aegyptiaca) with various body weights (50-70 g) and lengths (13-19 cm) were collected seasonally and randomly from the coastal area of the Mediterranean Sea in Port Said Governorate, Egypt from September-2019 till August-2020. Moribund or freshly dead specimens collected in aerated airbags and/or iceboxes were transferred to Food Hygiene and Bacteriology Unit, Animal Health Research Institute, Port Said for further bacteriological, and molecular examinations in particular for Vibrio infection. Fish were found to be infected with Vibrio alginolyticus based on the characteristic phenotypic and biochemical profiles with a total prevalence of 29.16%. During the study, the highest incidence of vibriosis among the naturally infected sole fish was observed in the summer season (31.43%), with the prevalence in the spring and winter seasons being equal (25.72% each). In contrast, the lowest incidence of infection was observed during autumn (17.14%). Molecular investigation of pure isolates using a specific set of primers targeting the 16S rRNA conserved gene of Vibrio species gave expected amplicons size of 663 bp.