Snakeheads (family Channidae) are air-breathing freshwater fishes native to Asia, Malaysia, Indonesia and tropical Africa. There are 29 separate species referred to as snakeheads but all are highly predatory as adults. In some species, adults can reach 6-feet in length. The first snakehead in the continental U.S. was collected in California in 1997, a second in Florida in 2000 and another in a Maryland pond in 2002. Recently, they have been documented from Wisconsin, Maine, Connecticut, Rhode Island, Maryland, North Carolina, Arkansas, Florida, and California. Although mostly limited to warmer waters, a giant snakehead weighing several pounds was caught in 2003 from the Wisconsin River, probably after being released by an aquarium enthusiast.
All species are highly predatory and undoubtedly prey on trout and other fishes. Their ability to breath air makes them extremely difficult to control and also means they can persist in wetlands and other shallow-water habitats. The northern snakehead occurs in colder waters than most other snakehead species and was the species collected in Maryland ponds.
Importation and the interstate transfer of any snakehead species is prohibited under federal law although some states still allow aquarium hobbyists to maintain the species. Snakeheads were cultured in Arkansas. Most occurrences in the wild are the result of illegal releases from aquariums. Natural reproduction has been documented in Maryland ponds, which were treated with rotenone during 2002 in what appear to have been successful efforts to eliminate the species from this area. Anglers should be on the lookout for snakeheads and report suspicious fish to proper authorities.
Source: Courtenay, W.R., Jr., and J.D. Williams. 2004. Snakeheads (Pisces, Channidae) - a biological synopsis and risk assessment. U.S. Geological Survey Circular 1251.