A small fish introduced to Hawaii in 1905 to control disease-carrying mosquitoes has become a major threat to the islands’ native freshwater species. The eastern mosquitofish, or Gambusia affinis , was brought from the southeastern United States and released into streams, drainage ditches and taro fields. Instead of feeding only on mosquito larvae, the invasive fish began preying on a wide range of native aquatic animals.
According to conservation assessments by the U.S. Fish and Wildlife Service (USFWS), mosquitofish have contributed to declines in several native Hawaiian damselflies, including threatened Megalagrion species. The fish’s aggressive feeding habits, rapid reproduction and ability to survive in different environmental conditions have made it particularly difficult to control.
