Evaluation of Fungal and Aflatoxin Contamination in Factory-made Feed in Rainbow trout Farms in Damghan City

Background and Aims: Aquatic feed consists of different components; the undesirable quality of each of them affects the quality of the meat produced. Fungi are agents of contamination and poison production in food. Aflatoxins are of particular importance among the toxins of fungi. This poison has the ability to transfer through feeds to fish and then humans. The aim of this study was to determine the amount of aflatoxin in the feed and to identify the fungal flora. Materials and Methods: In this study, 8 rainbow trout farms in Damghan city were evaluated for the assessment of fungal flora and total aflatoxin levels. 500 g sample of feed (pellet) was randomly prepared from the storeroom of the 8 fish farms. Fungi of Aspergillus Flavous and also fungal flora were isolated and identified by culture and slide culture method. Total aflatoxin measurement was performed using ELISA method. Results: A total of 11 genera (Aspergillus, Fusarium, Penicillium, Mucor, Scopulariopsis, Chrysosporium, Rhizopus, Absidia, Ulocladium, Alternaria, Pseudallescheria) were identified. The genera of Rhizopus and Aspergillus were the highest with 20.38% and 18.47% respectively. Among Aspergillus species, Aspergillus flavus was the highest with 48.44% and A. ochraceus had the lowest incidence of 10.34%. A. niger was also reported with 24.74% of the reported cases. The lowest frequency was found in the genus Chrysosporium with 1.28%. The average of total aflatoxin concentration was 5.36 ppb in the range of 2.03-11.64. Conclusions: The aflatoxin content in all samples from Rainbow trout consumption was less than the permitted level (20 ppb).