Photo credit: Gunther Schmida



Females grow to 6cm in length and males are 3.5cm long. The female can be identified by its larger size and a black mark on the side of the belly, above the vent.


This fish can tolerate a wide range of temperature and water conditions.


Has a reputation as a mosquito eater and is often referred to as the Mosquito Fish. Also eats ants, flies, aquatic bugs and beetles.


They breed in the warmer months and produce an average of 50 young, up to 9 times a year. The fertilised eggs develop for 3-4 weeks inside the females then larvae a few millimetres are born.


Birds, aquatic mammals, invertebrates such as crayfish and other fish.


Although they do not eat other fish, in many streams they out number native fish. They exhibit an aggressive fin-nipping behaviour and will often outcompete small native fishes for food and territory.

Introduction into Australia

This fish was introduced in the 1920s. Although it has a reputation as a mosquito eater, it appears no more effective at controlling mosquitos than Australian native fishes.

It is a major pest in the freshwaters of eastern NSW.

For more information on the impact of this pest species, download the Murray Darling Basin Authority Review