The gambusia is commonly known as the mosquito fish as it was introduced from America to control mosquito numbers in Australia in the 1920s.
Gambusia made a minimal impact on mosquito populations and are now a major pest in Australia. Each year a female may produce over 300 young, so their population has grown very quickly.
This population has a high survival rate because of their tolerance to many environmental conditions.
Gambusia are hardy fish and have a high tolerance of temperature, salinity, turbidity and dissolved oxygen in the water.
They are aggressive and will prey on native fish, amphibian eggs and water bugs. They aggressively compete with native species for food and habitat - they will even nip at the fins of smaller fish species, which can cause infection and death.
Gambusia have lead to the decline in nine native fish and over 10 frog species in Australia. Worldwide, gambusia have been linked to the decline of around 30 fish species.
Gambusia are a noxious fish in the NT and the possession of gambusia is banned.
You should not keep gambusia or ever release them into the wild.
If you have spotted a gambusia, take a photo if you can and report it to Fishwatch or aquatic biosecurity.
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Last updated: 27 June 2017