Species
Gambusia affinis
Threats Status
Unwanted Organism
Common Name(s)
Gambusia, mosquito fish
Family
Poeciliidae
Habitat
Gambusia occur in the shallow margins of ponds, wetlands and streams, particularly in the vegetative zone. They can tolerate poor water quality and tolerate a wide temperature range. They feeds on detritus material, small insects and zooplankton.
Description
Gambusia are relatively small (female up to 6cm, male up to 3.5cm) and have a greenish silvery shine. Female give birth to live young, consequently only one pregnant female is needed to start a new population.
Similar Species
Eastern mosquitofish (Gambusia holbrooki), sailfin molly (Poecilia latipinna), guppy (Poecilia reticulata), Xiphophorus maculatus
Threat To Plants
Extremely aggressive fish, that may attack other fish. Selective predation by Gambusia may alter zooplankton communities, which may have secondary effects on both phytoplankton and macrophyte communities. A single female produces several broods a year and around 50 offspring per brood—offspring which can reach sexual maturity in as little as three to four weeks. Given such prolific reproductive behaviour, Gambusia can quickly take over a waterway once they are introduced.
Distribution
Throughout Northland, Auckland, Waikato and the Bay of Plenty with isloated populations in Hawkse Bay and Wanganui. Absent from the South Island.
Measurements
Body length: <6cm (female), male <3.5cm (male)
Year Introduced
1930s
Reason For Introduction
Biological control of mosquito larvae
Colonisation History
The first successful shipment of Gambusia was released into an Auckland Botanical Gardens pond in 1930. Little information regarding successive releases is available but further transfers into Northland, Taranaki and Wellington in the 1930s are documented. Since then, Gambusia have continued to increase their range in many North Island waterways due to natural spread and by further illegal introductions.
Control Options
Cube root powder