Eastern Gambusia, Gambusia holbrooki Girard 1859

Other Names: Bore-drain Fish, Gambies, Gambusia, Mosquitofish, Mosquitofish, Mosquito-fish, Plague Minnow, Starling's Perch, Top Minnow

Male and female Eastern Gambusia, Gambusia holbrooki. Source: Gunther Schmida / http://www.guntherschmida.com.au. License: CC BY Attribution-Noncommercial-ShareAlike 3.0


In 1925, this native of North and Central America was intentionally introduced to Australia to control mosquito populations. Gambusia holbrooki is invasive on every continent except Antarctica. The species is in almost plague proportions in parts of Australia, and has had a significant impact on native fishes, invertebrates and frogs.

Identifying features: Olive-green above, sides greyish, belly silvery white; a single dorsal fin originating behind the level of the anal fin; females larger than males with a dark patch on the belly near the anus; mouth upturned, caudal peduncle long; males with long anal fin rays.

Cite this page as:
Martin F. Gomon & Dianne J. Bray, Gambusia holbrooki in Fishes of Australia, accessed 19 Apr 2024, https://fishesofaustralia.net.au/home/species/3636

Eastern Gambusia, Gambusia holbrooki Girard 1859

More Info


Intentially released (from SE United States of America) into Australia to control mosquitoes, Eastern Gambusia are now widespread throughout much of mainland Australia, and also occur in northern Tasmania.

In 1991, a population was discovered in a farm dam in the Tamar River catchment, northern Tasmania. Despite eradication attempts, the species is now appears to be established in the Tamar Valley.

Eastern Gambusia prefer warm, gently flowing or still waters, and are usually found amongst aquatic vegetation near the water's edge. They inhabit lakes, dams, marshes, billabongs, aqueducts and slow-flowing streams, and are extremely tolerant of a wide range of environmental conditions. They survive in water temperatures ranging from almost freezing to 38ºC, in water bodies with very low dissolved oxygen levels and in salinities ranging from freshwater to fully marine.


Dorsal-fin rays 6-8 (usually 7); Anal-fin rays 9-11 (usually 10); Vertebrae 31-33; Gill rakers 13-15

Body stout with a deep rounded belly (particularly in females, and more so when carrying a brood of young); upper surface flattened, especially the head; mouth small, upturned and protrusible, lower jaw a little longer than upper; eyes large.

Large scales cover head and trunk (28-32, usually 30-31 along side); no lateral line.

Dorsal fin single, sort-based, soft-rayed, positioned well back on trunk, fin high and rounded; anal fin small and rounded in females, elongate and modified into a gonopodium in males; caudal fin rounded.


Females to 6 cm SL; males to 3.5 cm SL.


Generally greenish olive to brownish on back, sides grey with a bluish sheen, belly silvery; some dark speckling dorsally and on caudal fin; females with a large black blotch surrounded by a golden patch just above vent.


Primarily carnivores - feed on a range of small freshwater invertebrates, windblown terrestrial insects, and the eggs, larvae and juveniles of native fishes and frogs.


Eastern Gambusia are live-bearers. The front rays of the male’s anal fin are modified to form a gonopodium which is used to internally fertilise eggs.

Breeding occurs during the warmer months and females produce about 50 live young in each batch with up to 9 batches per year.

Zane et al. (1999) found that females store sperm, and that 90% of all broods were sired by multiple males. The fertilised eggs develop inside the female, and the young are a few millimetres long when born.


Gambusia holbrooki has been ineffective in controlling mosquitos, and is now a widespread pest species. It is highly adaptable to changing environmental conditions, and persists in most aquatic habitats, except where cool temperatures affect the reproductive cycle.

Eastern Gambusia have been implicated in the decline of at least 9 fish species and more than 10 frog species in Australia. They compete with native fishes for habitat and food, and are very aggressive towards other species.

Species Citation

Gambusia holbrooki  Girard 1859, Proc. Acad. Nat. Sci. Philad. 11: 62. Type locality: Palatka, Florida, Charleston, South Carolina, U.S.A.


Martin F. Gomon & Dianne J. Bray

Eastern Gambusia, Gambusia holbrooki Girard 1859


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Quick Facts

CAAB Code:37244001



Max Size:Females 6 cm; males 3.5 cm

Native:Introduced (noxious & invasive)

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