Waipio Valley Stream Restoration Study

Fish: Introduced Species

Scientific name: Gambusia affinis
Common name(s): Mosquitofish

Gambusia affinis

Status: Introduced

Habitat: Mosquitofish are found almost everywhere. They can live in slow-moving streams and streams with poor water quality.

Preferred Area of Stream: Slow water areas such as isolated side pools, deep pools and slow runs and all wetland areas.

Range in Hawai‘i: Common on all Hawaiian Islands

Diet: Voracious predator, will eat any insect or small fish of fish eggs that are smaller than itself.

Predators: Birds such as ‘auku‘u (black-crowned night-herons) and introduced fish

Fact: Mosquitofish are one of the most harmful introduced species in Hawaiian streams, and this small fish causes some of the greatest harm to Hawaiian aquatic ecosystems. They prey upon small ‘o‘opu, transmit disease and parasites to native fish, and compete with native fish for food and living space. They also have played a major role in causing some species of Hawaiian damselflies to go extinct.