Zearalenone
Studies on the effects of zearalenone (ZEN) in farm animals have mainly focused on dysfunction or structural disorders of the reproductive tract. Several studies have confirmed that ZEN modulates estrogen receptor-dependent gene expression in aquatic species, thus affecting the reproduction of fish.
This has been shown in zebrafish (Danio rerio), where the exposure to ZEN reduced spawning frequency, or changed the relative fecundity from one generation to the next. Together with affecting reproduction, ZEN was reported to show genotoxic effects such as defects in heart and eye development and upward curvature of the body axis of zebrafish.
Fumonisins
In aquaculture species, fumonisin B1 (FB1) has been generally associated with reduced growth rate, feed consumption and feed efficiency ratio, as well as impaired sphingolipid metabolism. In rainbow trout, FB1 has been shown to induce changes in the liver’s sphingolipid metabolism at levels lower than 100 ppb and was able to induce liver cancer in 1-month-old trout.
According to the literature, ingestion of FB1 by carp resulted in lesions in liver and pancreas already at concentrations as low as 500 ppb. Performance parameters such as average weight gain and body weight dropped after dietary administration of low doses of FB1. FB1 affected the performance of Nile tilapia as well. Reduced average weight gain and increased Sa/So ratio have been reported in the literature.
Ochratoxins
Studies on the toxicity of ochratoxin A (OTA) in aquatic animals are very scarce. The few available studies reported effects such as severe degeneration and necrosis of kidney and liver leading to inferior weight gain, poorer FCR, lower survival rates and hematocrit levels. OTA is also immunosuppressive and one study conducted on catfish showed how animals exposed to this mycotoxin become more susceptible to pathogenic infections.