The aim of this study was to determine the occurrence of fungi and aflatoxins in fish feeds. We analyzed 36 samples of feed for fish, with two protein compositions (juvenile/fattening) and two forms of use (sealed/open). Aspergillus and Penicillium species were counted, isolated and identified, the toxic capacity of Flavi strains was measured and aflatoxins in the feed were researched. The mean fungal counts ranged from 2.96 to 4.00 log10 CFU/g and there was no significant difference between treatments. The most isolated species were Aspergillus flavus, Eurotion spp. and Penicillium implicatum. We concluded that the feeds studied had high fungal counts; the isolated Aspergillus flavus strains were not producers of aflatoxin; and aflatoxin was not detected in the feed samples analyzed.