Isolation and morphological identification of aflatoxigenic Aspergillus flavus in finished feed for farmed Nile tilapia, Oreochromis niloticus (Linnaeus, 1758)

The most important problem facing the aquaculture sector today is the foodborne toxin exposure, such as aflatoxins. Aflatoxins are produced mainly by two fungal species, Aspergillus flavus and Aspergillus parasiticus that are normally; occur in hot and humid regions of the world. Practically, it is not possible to destroy the contaminated feed; therefore, to identify the fungal isolates is very important for taking remedial measures against aflatoxin contamination in fish. In this study, we isolated fungal isolates from five types of fish feed that prepared for farmed Nile tilapia. To know the characteristics features of these fungal isolates, three differential media including Potato dextrose (PD) broth, Czapek’s yeast extract agar (CYA) and Yeast extract peptone dextrose broth (YEPD) were used for differentiation of Aspergillus species, colonizing in feeds comparing with standard cultures. According to the morphological features, all the isolates from the fish feeds were identified as Aspergillus flavus species in three of the culture media.