Isolation and identification of fungal flora of gill and skin and determination of relationship between them in rainbow trout in Mazandaran Province

Objective: Vertebrates aquatic animals are susceptible to a variety of pathogenic organisms, including fungi. In fact, the first clinical report of a fungus infecting a vertebrate was of a fish. Many of the fungi that affect fish are considered opportunists, attacking the fish when they are stressed or immunocompromised because of unfavorable environmental conditions, or secondary to bacterial or viral infections, or when they have lost their mucus protection because of trauma or excessive handling. Therefore, this study was carried out to indicate fungal flora of gill and skin and determination relationship between them. Method & Materials: The samples were obtained from ten fish farms (sixty fish) in Mazandaran Province and transferred to mycology laboratory in ice boxes. The samples were inoculated in culture media ((Sabourodextrose agar + choloramphenicol)-corn meal agar-Czapeks agar) and also slide culture and directly examined. Fungal isolates obtained was compared with the morphological forms presenting in direct examination. Results & Conclusion: Thirty seven species of fungi were isolated with dominant species of Penicillum (16/22 %) and the lowest number of Mucor and Achlya groups (5/41%) in gill were identified and thirty nine species of fungi were isolated with dominant species of Penicillum (20/51 %) and the lowest number of Helminthosporium species (2/56%) in skin were identified. All the isolated species belonged to the following groups: Penicillum, Mucor, Fusarium, Paecilomyces, Acremonium. Aspergillus, Helminthosporium, Saprolegnia, Achlya and Alternaria. It is concluded that the above-mentioned isolated fungi play an important role in fish diseases under unfavorable conditions. In this study, there was a significant correlation between the level of contamination of skin and gill in isolated samples. (P< 0/05 Chi square test)