Waipio Valley Stream Restoration Study

Fish: Introduced Species

Scientific name: Xiphophorus helleri
Common name(s): Green swordtail

Xiphophorus helleri

Status: Introduced

Habitat: Swordtails are found in streams and large reservoirs, like Nu‘uanu and Ho‘omaluhia reservoirs on O‘ahu. They prefer quiet pools and the slower-moving edges of the stream.

Preferred Area of Stream: Deep water pool areas, and slow to medium velocity runs

Range in Hawai‘i: Common on all Hawaiian Islands

Diet: Carnivorous, eats small fish, worms, small shrimp, and insects

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

Fact: Large females can lay up to 100 eggs at a time. They also carry worms and parasites that infect the native ‘o‘opu fish population. One of the most widespread introduced fish in Hawai‘i, and harmful because it eats native insects such as damselflies and young ‘o‘opu. Although these fish were put in streams to control mosquitoes, they have had little impacts because mosquitoes live in puddles in the forest, not in the flowing stream where green swordtails live.