Mycotoxin Contamination in Aquaculture Systems: Sources, Toxicological Effects and Implications for Food Safety

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that often contaminate plant-based feed ingredients used in aquaculture. The ongoing replacement of fishmeal and fish oil with cereals and oilseeds increases the risk of fish being chronically exposed to multiple mycotoxins. This review aims to provide a short overview of mycotoxin contamination in aquaculture systems. This review summarises the occurrence, exposure routes, toxicokinetics, and biological effects of the main regulated mycotoxins, such as aflatoxin B1 (AFB1), deoxynivalenol (DON), zearalenone (ZEN), fumonisins, and ochratoxin A (OTA), as well as emerging compounds, including beauvericin (BEA), enniatins (ENNs), and Alternaria toxins. Although environmental factors and post-harvest processes may also contribute, feed is identified as the primary contamination source. Mycotoxins show limited carry-over into fish tissues, with the liver being the main site of accumulation and biotransformation; meanwhile, muscle residues remain relatively low, yet still relevant in terms of food safety. The toxic effects are multifactorial and include oxidative stress, apoptosis, immune dysregulation, endocrine disruption and metabolic disorders. There is increasing evidence highlighting the importance of co-exposure scenarios, where additive or synergistic interactions can enhance toxicity. The study of emerging and modified ('masked') mycotoxins remains insufficient, especially in vivo, which complicates risk assessment. Conclusions: Improved monitoring, a better understanding of combined toxicity, and the harmonisation of regulatory limits are essential. The development of effective mitigation strategies is necessary to ensure the sustainability of aquaculture production and food safety, particularly in the context of an increasing reliance on plant-based feeds.