Waipio Valley Stream Restoration Study

Fish: Introduced Species

Scientific name: Poecilia mexicana
Common name(s): Mexican molly, Tabai

Poecillia mexicana

Status: Introduced

Habitat: Mexican mollies like slow-moving streams and pools.

Preferred Area of Stream: Pools and slow runs, also side pool areas. They are extremely hardy and can also live in canals that have been paved with concrete.

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 introduced fish

Fact: This fish was brought in as an aquarium fish and is highly destructive to native freshwater species. Mollies compete with native fish for food and living space and have harmful parasites which they spread to native ‘o‘opu (stream fish). Mollies lay 80-100 eggs every 5-8 weeks. Often they are the most common fishes, along with mosquitofish (Gambusia affinis), in altered Hawaiian streams. Experiments have shown that Mexican mollies in aquariums will quickly consume all ‘o‘opu hinana [young native stream fish] placed into the same aquarium.