study of external fungal flora of the skin and gills of rainbow trout in the Shahrood city

The present study aimed to isolate and identify superficial fungal flora of the skin and gills of rainbow trout in the Shahrood city. Specimens were taken from the gill and skin of 100 rainbow trout from 5 fish farms during winter and spring, then were cultured on SDA and GPA medium. Isolated fungi were identified according to the colony morphologies and microscopic characteristics. In this study, 11 genera of fungi, including Aspergillus sp., Fusarium sp., Phoma sp., Cladosporium sp., Alternaria sp., Penicillium sp., Rhodotorula sp., Candida sp., Geotricum sp., Trichosporon sp., and Malassezia sp. were isolated that Phoma sp. and Fusarium sp. are pathogenic aquatic fungi. The most prevalent fungi were related to Aspergillus (16.66% on the skin and 23.8% in gill). Variety of isolated fungi indicated that sanitary and environmental condition of the farms are unfavourable and would cause a decrease in total production, an increase of fungal infection and treatment cost. Ecological differences play an important role in the species diversity of superficial fungal flora.