Fish feed mycobiota and aflatoxins in round fish tissues

Round fish is one of the most consumed fish in Brazil. Farmed fish feed is based mainly on grains, which are susceptible to contamination by mold and mycotoxins. Aspergillus spp., Penicillium spp. and Fusarium spp. are the major mycotoxins producers. The presence of potentially toxigenic fungi in the diet is a concern due to the possibility of cumulative toxins in fish tissues, becoming a risk to food safety. This study aims to assess the mycobiota of fish feed and the occurrence of aflatoxin residues in round fish tissues. Feed and fish samples were collected from fish farming and fish pay properties. Feed was submitted to mold counting and mold identification. The round fish liver and muscle were submitted to the detection and quantification of aflatoxins B₁ , B₂ , G₁ and G₂ by high-performance liquid chromatography.

In evaluated feed, mold counts in the samples ranged from 2.0 to 4.7 log colony forming units g^-1 and the major genera found were Penicillium (61.5%) and Aspergillus (34.6). Aflatoxin B₁ (AFB₁ ) was detected in 70% liver samples and 43.3% muscle samples, at levels up to 5.70 and 1.13 μg kg^-1 , respectively.

It is concluded that, although the levels were lower than those recommended by Brazilian legislation, round fish are being exposed to diets naturally contaminated by aflatoxins and are susceptible to toxins accumulation in tissues. Therefore, regulations regarding feed should consider limits for mold and aflatoxin contamination in fish edible tissues should be monitored in order to ensure consumers' safety. © 2021 Society of Chemical Industry.