The most common mycotoxin is aflatoxin. It can be very carcinogenic to both humans and animals. Aflatoxin is produced by two species of Aspergillus, A. flavus and A. parasiticus, which are known to affect plants including cereal grains, figs, nuts, and tobacco.[1] Cereal grains are one of the main ingredient in animal feed. The animals most at risk of having serious problems with aflatoxins are trout, ducklings, and pigs, while cattle are less at risk.