Invasive species
A fish moved by people outside its natural range that spreads and harms native wildlife or people's livelihoods.
Also: introduced species, alien species, exotic fish
Many fish have been moved by people, for food, sport, aquariums or by accident in ships' ballast water. Most introduced fish fail or cause little trouble, but some become invasive. The Nile perch, put into Lake Victoria in the 1950s, helped drive many native cichlids to extinction. Lionfish from the Indo-Pacific spread along the western Atlantic from the 1980s. Asian carps crowd American rivers. In India, the African catfish, tilapia and the Amazon sailfin catfish have spread in rivers, lakes and reservoirs, and farming of the African catfish is banned.