الفهرس | Only 14 pages are availabe for public view |
Abstract A wide variety of fungi plays a role as a pathogenic agent in fish which act as a secondary or even as a primary invadors. Also there are many fungi occur as saprophyte on fish or con tamenate its food stuff. This study was carried out on 400 fish sample representing 100 sample of Tilapia, 120 sample of catfish, 110 carp, 70 sample of Mugil from different localities of Egyptian fresh water sources, from Baher Mousa, Esmaelia canal, San El-hagar, Abbasa artificial spawning center and Seuz canal university researching unite representing both natural and artificial fish breeding system. The samples were examined for the presence of fungi which may cause diseases for fish or whcih found as a saprophyte by using the direct isolation technique on Sabaroud’s dextrose agar with chloramphenicol and Czapek’s media. The results obtained revealed isolation of some fungi and yeasts from the skin and gills of fish they were 9 genera of fungi from apparently healthy fish representing Aspergillus: Penicillium: Fusarium: Mucor; Rhizopus; Absidia; Alternaria: Chladosporium: Hlmenthosporium and one genera was isolated form fish showing skin and gill infection representing genus Saprolegnia. 2 genera of yeasts were also isolated from apparently healthy fish representing Candida and Rhoduterulla. Some f~ngi and yeasts were isolated from liver, spleen and kidneys of some fish as Aspergillus from liver and kidneys, Penicillium from kidneys, Mucor from kidneys, Candida from spleen ~nd Kidneys and Rhoduterulla from kidneys. The results obtained revealed that the fungus Saprolegnia was the most important isolated fungus which affect fish causing losses. So that more idenitification and experimental infection were carried out, which revealed that the isolated species was saprolegnia parasitica. Seasonal examination of fish revealed that fungus Saprolegnia intects fish specially at low water temperature which may be act as a predisposing factor. Handling, injury, spawning period may ’also playa role in infection. Results obtained from experimentally infected fish revealed that Saprolegnia reproduced by naturally infected fish or mycelial mats of the fungus Saprolegnia cultured on Sabaroud’s agar with hemp seed as a source of infection. The fish under experiment were healthy some fish with intact skin, others were injured. The experiment revealed that Saprolegnia affect fish only from the skin and gills as a primary pathogen. Wounded fish were highly susciptible to fungal infection. Intrapritoneal and intraMuscular infection revealed negative results for Saprolegnia is. |