Mycotoxins are natural toxicants produced by fungi. These fungi affect grains, especially under warm and humid conditions. Grains will be increasingly used as animal feed in aquaculture, resulting in a major concern regarding the health status of fish. Hence, in a series of studies, specific mycotoxins are being analysed according to physiological parameters and the immune system of carps - one of the most common fish in aquaculture worldwide. This research is of high relevance for sustainability, especially under the circumstances of overfishing and climate change.