Fumonisins are a group of mycotoxins discovered in 1988, in South Africa, produced by a number of Fusarium species, notably F. verticillioides, F. proliferatum, and F. nygamai. All strains are considerably variable in toxin producing ability. The group includes fumonisin B1 (FB1), FB2 and FB3, however the most abundantly produced fumonisin is FB1. Fumonisins disrupt the metabolism of sphingolipids (important components of cellular membranes and neural tubes) through the inhibition of the enzyme ceramide synthase. Fumonisins are cancer promoters and possible carcinogens to humans (group 2B, IARC 2002). These mycotoxins are hepatotoxic, nephrotoxic and immunosuppressive for several terrestrial species. In aquaculture, fumonisins have been generally associated with reduced growth rate, feed consumption and feed efficiency ratio, as well as impaired sphingolipid metabolism. However, scarce information is available on the effects of fumonisins on most important aquaculture species. Experiments conducted on carp (Cyprinus carpio L.), reported the presence of scattered lesions in the exocrine and endocrine pancreas and inter-renal tissue, probably due to ischemia and/or increased endothelial permeability. Loss of body weight and alterations of hematological and biochemical parameters after consumption of fumonisin-contaminated feed were reported in the literature. Nile tilapia fingerlings were reported to be sensitive to relatively low-doses of fumonisin, resulting in the decrease of average weight gain, and disruption of the sphingolipid metabolism. Studies in shrimp are scarce, however the available literature, suggests that Litopenaeus vannamei is sensitive to FB1. A study from 2013 showed that white shrimp fed FB1 at levels from 20 to 200 µg kg −1 had a reduction in soluble muscle protein concentration and reported changes in myosin thermodynamic properties after 30 days of exposure to FB1. The same study reported marked histological and meat quality changes in shrimp fed a diet containing FB1 at 200 µg kg −1. The BIOMIN mycotoxin survey for Asia reveals that 82% of samples analyzed contain fumonisins, with an average level of 1833 µg kg −1. Rice bran, showed a prevalence of fumonisin of 61% and a relatively low average level, if compared to other commodities such as corn, corn gluten meal and DDGS (2950, 13063, 8117 µg kg −1 respectively), however even low levels are shown to produce negative effects in some species such as white shrimp (L. vannamei). Corn, CGM and DDGS presented a prevalence of 96%, 100% and 97% respectively, indicating that almost every sample analyzed contained fumonisins. These concentrations are high and may harm production, especially if we consider the risk of synergism with other mycotoxins, pathogens and antinutrients! As fumonisins are relatively stable to temperature and processing conditions, it is expected to find them in finished feeds as well.