Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.
Native to northern, central, and western Africa, Hemichromis letourneuxi, or African jewelfish, is a fish species that can thrive in fresh and brackish waters. It is a resilient species that is tolerant of highly saline and oxygen deficient environments. A popular ornamental hobbyist fish, the species was first documented as introduced in south Florida in the Hialeah Canal-Miami River Canal system, Miami area, by Rivas in 1965. It has rapidly expanded in recent decades and can now be found throughout the southern half of the Florida peninsula. No other established populations have been confirmed outside of the contiguous United States and the native range. Results from mesocosm studies show that H. letourneuxi increases mortality rate of native fish, snails, and shrimp relative to a native predator or abiotic stressors. In another mesocosm study, H. letourneuxi suppressed native sunfish (Lepomis marginatus) spawning through its aggressive behavior. It is hypothesized that H. letourneuxi may compete with native sunfishes for spawning sites, but detailed evidence is lacking at present. Climate match for the contiguous United States is medium, with Florida representing the highest match. Given the history of negative impacts of introduction and the medium climate match to the contiguous United States, the overall risk assessment category for H. letourneuxi is high.