Eastern mosquitofish

species of fish

The eastern mosquitofish, eastern gambusia, or mosquito fish (Gambusia holbrooki) is a fish that belongs to the Poeciliidae family.[1] It is from the eastern United States[3] but human beings brought it to many other parts of the world, such as Hawaii, Puerto Rico, and Australia, where it has caused problems as an invasive species.[3][4]

Gambusia holbrooki
Gambusia holbrooki.png
Top: female/Bottom: male
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cyprinodontiformes
Family: Poeciliidae
Genus: Gambusia
G. holbrooki
Binomial name
Gambusia holbrooki
Girard, 1859
  • Heterandria holbrooki (Girard, 1859)
  • Schizophallus holbrooki (Girard, 1859)
  • Zygonectes atrilatus Jordan & Brayton, 1878

The adult male eastern mosquitofish grows to 3.5 cm and the female to 6.0 cm. It is green or brown on top and blue, white or silver on the bottom. It has large eyes and one dorsal fin and a round tail fin.[4]

This fish likes to live in fresh water but can live in water that has some salt. It can survive cold and warm temperatures. It eats insects and their larvae.[4]

People brought the eastern mosquitofish to Hawaii in the 1910s and to Australia in the 1920s and set it free there. They thought it would eat mosquito larvae so there would be fewer mosquitoes. But the eastern mosquitofish did not eat more mosquitoes than the fish that were already in Australia did. The eastern mosquitofish outcompetes other fish and bites their tails[4] or even eats them. It can kill larger fish by damaging their fins. In the western United States, the eastern mosquitofish killed or outcompeted many other fish that were better at controlling mosquitoes than it is.[3] After people put eastern mosquitofish in a body of water, there may be an algal bloom because the eastern mosquitofish eats or kills all the fish that usually eat the algae.[3]

This fish likes to eat frog eggs and tadpoles. It is one reason why the green and golden bell frog is endangered in Australia[5] and the Chiricahua leopard frog in Arizona.[3]

The fish has 50-300 eggs at a time. The eggs stay inside the female's body until they hatch. It takes the new fish two months to become adults. Eastern mosquitofish can do this several times each year.[4]

The western mosquitofish G. affinis and eastern mosquitofish G. holbrooki used to both be called G. affinis because people thought they were the same species. They are not. According to the IUCN Global Invasive Species Database, most records in Australia that say "G. affinis" really refer to G. holbrooki.[6]


  1. 1.0 1.1 NatureServe (2013). "Gambusia holbrooki". The IUCN Red List of Threatened Species. p. e.T202394A18232445. doi:10.2305/IUCN.UK.2013-1.RLTS.T202394A18232445.en. Retrieved June 28, 2020.
  2. Froese, Rainer and Pauly, Daniel, eds. (2019). "Gambusia holbrooki" in FishBase. August 2019 version.
  3. 3.0 3.1 3.2 3.3 3.4 Nico, L.G.; Fuller, P.; and Neilson, M.E. (September 27, 2001). "Gambusia holbrooki Girard, 1859: U.S. Geological Survey, Nonindigenous Aquatic Species Database". Gainesville, FL: United States Geological Survey. Retrieved June 28, 2020.
  4. 4.0 4.1 4.2 4.3 4.4 Mark McGrouther (January 18, 2019). "Eastern Gambusia, Gambusia holbrooki Girard, 1859". Australian Museum. Retrieved June 28, 2020.
  5. J-M Hero; W. Osborne; R. Goldingay; K. McCray; L. Shoo (May 6, 1999). "Litoria aurea: Green and Golden Bell Frog". Amphibiaweb. Retrieved June 13, 2020.
  6. "Gambusia affinis". IUCN Global Invasive Species Database. June 21, 2010. Retrieved June 28, 2020.