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  • Mosquitofish pair (Photo: Bob McDowall)
  • Gambusia affinis (Photo: WikiMedia Commons)
  • Gambusia affinis (Photo: WikiMedia Commons)
  • Gambusia affinis (Photo: WikiMedia Commons)
Common name
tes (Cantonese, Hong Kong), Barkaleci (Albanian), pez mosquito (English, Dominican Republic), Gambusino (Spanish), western mosquitofish (English), Kounoupopsaro (Greek), guayacon mosquito (Spanish), live-bearing tooth-carp (English, Hong Kong), Western mosquitofish (English, USA), Dai to ue (Cantonese, Hong Kong), Obyknovennaya gambuziya (Russian), Mosquito fish (English), San hang ue (Cantonese, Hong Kong), Koboldkärpfling (German), Gambusie (French, Canada), Topminnow (English, Hong Kong), Isdang canal (Tagalog), Gambusia (English), Kadayashi (Japanese), Gambuzia pospolita (Polish), Gambuzia (Portuguese), Gambuzija (Russian, Ukraine), Texaskärpfling (German), Silberkärpfling (German)
Heterandria affinis , Baird & Girard, 1853
Gambusia affinis , (Baird & Girard, 1853)
Gambusia affinis affinis , (Baird & Girard, 1853)
Zygonectes patruelis , (Baird & Girard, 1853)
Heterandria patruelis , Baird & Girard, 1853
Gambusia patruelis , (Baird & Girard, 1853)
Zygonectes gracilis , (Girard, 1859)
Gambusia gracilis , Girard, 1859
Haplochilus melanops , Cope, 1870
Zygonectes brachypterus , Cope, 1880
Fundulus inurus , (Jordan & Gilbert, 1882)
Zygonectes inurus , Jordan & Gilbert, 1882
Gambusia humilis , Gunther, 1866
Similar species
Gambusia holbrooki, Poecilia reticulata, Xiphophorus maculatus, Poecilia latipinna
Gambusia affinis is a small fish native to the fresh waters of the eastern and southern United States. It has become a pest in many waterways around the world following initial introductions early last century as a biological control agent for mosquitoes. In general, it is considered to be no more effective than native predators of mosquitoes. The highly predatory mosquito fish eats the eggs of economically desirable fish and preys on and endangers rare indigenous fish and invertebrate species. Mosquito fish are difficult to eliminate once established, so the best way to reduce their effects is to control their further spread. One of the main avenues of spread is continued, intentional release by mosquito-control agencies. G. affinis is closely related to he eastern mosquito fish (G. holbrooki), which was formerly classed as a sub-species. Their appearance, behaviour and impacts are almost identical, and they can therefore be treated the same when it comes to management techniques. Records of G. affinis in Australia actually refer to G. holbrooki.
Species Description
A stout little fish, the back a little arched in front of the dorsal fin and the belly deep in front of the anal. The head is large with a flattened upper surface, the mouth small, upturned and protrusible, and not reaching as far back as the front of the eyes. The eyes are very large relative to the body. The single, soft-rayed dorsal fin is short-based, high and rounded, while the caudal peduncle is long, deep and compressed, and the caudal fin is rounded. The head and trunk are covered with large scales and there is no lateral line. The back is a greenish olive to brownish, the sides grey with a bluish sheen, and the belly a silvery white. A well-defined black spot on the upper rear abdomen is surrounded by a golden patch above and behind the vent. In mature females there is also a black patch above and somewhat forward of the vent. The ventral surface of the head is a steely blue with a diagonal chin stripe below the eyes. The eyes are greyish to olive, the dorsal fin has small black spots, and the caudal fin has several indistinct cross rows of small black spots. The anal, pelvic and pectoral fins are a translucent pale amber. (McDowall, 1990). Males grow to 40mm in length, while females reach 70mm long (FishBase, 2003).
Gambusia affinis is extremely similar to the closely related G. holbrooki, and until relatively recently they were classed as sub-species rather than distinct species. As such, their impacts and behaviour are virtually identical, and the same management techniques will work for both species.

Although hybrids between G. holbrooki and G. affinis can occur, they are unusual in natural populations (Wooten and Lydeard 1990).

Lifecycle Stages
Males mature at about 21mm long and a month old; females at 28mm and six weeks old (McDowall, 2000)
Used as live food for carnivorous aquarium fishes and also used as mosquito control (FishBase, 2003).
Habitat Description
Benthopelagic; non-migratory; lives in fresh and brackish water with a pH range of 6.0 - 8.0 and usually at temperatures between 12 - 29°C (FishBase, 2003). Mosquito fish are a remarkably hardy species, surviving in waters with little oxygen, in high salinities (including twice that of sea water) and temperatures of up to 42°C for short periods (McCullough, 1998). They are most abundant in lower reaches of streams, where they inhabit brackish, standing to slow-flowing water. They are most common in vegetated ponds and lakes, backwaters and quiet pools of streams (FishBase, 2003).
Live-bearer. Several times a year mosquito fish produce moderate numbers of young, which are protected by the mother but which become immediately independent. Brood size is usually around 60 young, but large females can carry more than 300 (McDowall, 2000).
Feeds on zooplankton, small insects and detritus, (FishBase, 2003).
Brought to New Zealand by ship. (McDowall, 1990)Widely introduced for mosquito control. (FishBase, 2003)Survivors of the sea voyage to New Zealand were released into a pond in the Auckland Botanical Gardens. (McDowall, 1990)

Principal source: FishBase, 2004. Species profile Gambusia affinis Mosquito fish

Compiler: IUCN/SSC Invasive Species Specialist Group (ISSG)


Publication date: 2010-06-21

Recommended citation: Global Invasive Species Database (2024) Species profile: Gambusia affinis. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=126 on 23-07-2024.

General Impacts
Adult Gambusia affinis are extremely aggressive and attack other fish, shredding fins and sometimes killing them. Controversy has followed the introduction of mosquito fish, as they have been accused of being little better at destroying mosquitoes than native fish species, as well as being responsible for eliminating many of these same species (Myers, 1965; Haas et al., 2003). Selective predation by mosquito fish has also been shown to alter zooplankton, insect and crustacean communities (McDowall, 1990). Mosquito fish are potential hosts of helminth parasites, which have been transmitted to native fishes (FishBase, 2003).
Management Info
Chemical: The poison Rotenone, which works by inducing hypoxia in fish, may be used to eliminate mosquito fish from small areas of permanent water. Rotenone is indiscriminate, so non-target species ideally need to be removed prior to its application. Fish affected by Rotenone come to the surface to seek oxygen, so any remaining non-target species may be removed at this stage (Willis & Ling, 2000).
Countries (or multi-country features) with distribution records for Gambusia affinis
Informations on Gambusia affinis has been recorded for the following locations. Click on the name for additional informations.
Lorem Ipsum
Location Status Invasiveness Occurrence Source
Details of Gambusia affinis in information
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Species notes for this location
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Management notes for this location
Ecosystem services:
Impact information
Adult Gambusia affinis are extremely aggressive and attack other fish, shredding fins and sometimes killing them. Controversy has followed the introduction of mosquito fish, as they have been accused of being little better at destroying mosquitoes than native fish species, as well as being responsible for eliminating many of these same species (Myers, 1965; Haas et al., 2003). Selective predation by mosquito fish has also been shown to alter zooplankton, insect and crustacean communities (McDowall, 1990). Mosquito fish are potential hosts of helminth parasites, which have been transmitted to native fishes (FishBase, 2003).
[3] Predation
[3] Environmental Ecosystem - Habitat
  • [3] Reduction in native biodiversity
Management information
Chemical: The poison Rotenone, which works by inducing hypoxia in fish, may be used to eliminate mosquito fish from small areas of permanent water. Rotenone is indiscriminate, so non-target species ideally need to be removed prior to its application. Fish affected by Rotenone come to the surface to seek oxygen, so any remaining non-target species may be removed at this stage (Willis & Ling, 2000).
31 references found for Gambusia affinis

Management information
Centre for Environment, Fisheries & Aquaculture Science (CEFAS)., 2008. Decision support tools-Identifying potentially invasive non-native marine and freshwater species: fish, invertebrates, amphibians.
Summary: The electronic tool kits made available on the Cefas page for free download are Crown Copyright (2007-2008). As such, these are freeware and may be freely distributed provided this notice is retained. No warranty, expressed or implied, is made and users should satisfy themselves as to the applicability of the results in any given circumstance. Toolkits available include 1) FISK- Freshwater Fish Invasiveness Scoring Kit (English and Spanish language version); 2) MFISK- Marine Fish Invasiveness Scoring Kit; 3) MI-ISK- Marine invertebrate Invasiveness Scoring Kit; 4) FI-ISK- Freshwater Invertebrate Invasiveness Scoring Kit and AmphISK- Amphibian Invasiveness Scoring Kit. These tool kits were developed by Cefas, with new VisualBasic and computational programming by Lorenzo Vilizzi, David Cooper, Andy South and Gordon H. Copp, based on VisualBasic code in the original Weed Risk Assessment (WRA) tool kit of P.C. Pheloung, P.A. Williams & S.R. Halloy (1999).
The decision support tools are available from: http://cefas.defra.gov.uk/our-science/ecosystems-and-biodiversity/non-native-species/decision-support-tools.aspx [Accessed 13 October 2011]
The guidance document is available from http://www.cefas.co.uk/media/118009/fisk_guide_v2.pdf [Accessed 13 January 2009].
Champion, P. Clayton, J. and Rowe, D. 2002. Alien Invaders Lake Managers� Handbook. Ministry for the Environment.
Summary: Available from: http://www.mfe.govt.nz/publications/water/lm-alien-invaders-jun02.pdf [Accessed 3 February 2005]
Copp, G.H., Garthwaite, R. and Gozlan, R.E., 2005. Risk identification and assessment of non-native freshwater fishes: concepts and perspectives on protocols for the UK. Sci. Ser. Tech Rep., Cefas Lowestoft, 129: 32pp.
Summary: The discussion paper presents a conceptual risk assessment approach for freshwater fish species that addresses the first two elements (hazard identification, hazard assessment) of the UK environmental risk strategy The paper presents a few worked examples of assessments on species to facilitate discussion.
Available from: http://www.cefas.co.uk/publications/techrep/tech129.pdf [Accessed 1 September 2005]
Englund, R.A. 1999. The impacts of introduced poeciliid fish and Odonata on the endemic Megalagrion (Odonata) damselflies of Oahu Island, Hawaii. Journal of Insect Conservation 3:225-243.
Gambusia Control Homepage, 1998.
Summary: A website focused on the possibilities of biological control of Gambusia affinis.
Available from: http://www.gambusia.net/ [Accessed 21 July 2003]
IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
Summary: The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been globally evaluated using the IUCN Red List Categories and Criteria. This system is designed to determine the relative risk of extinction, and the main purpose of the IUCN Red List is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable). The IUCN Red List also includes information on taxa that are categorized as Extinct or Extinct in the Wild; on taxa that cannot be evaluated because of insufficient information (i.e. are Data Deficient); and on taxa that are either close to meeting the threatened thresholds or that would be threatened were it not for an ongoing taxon-specific conservation programme (i.e. are Near Threatened).
Available from: http://www.iucnredlist.org/ [Accessed 25 May 2011]
McKay, S.; Clunie, P.; Gillespie, G.; Raadik, T.; Saddlier, S.; O Brien, T.; Ryan, T.; and Aland, G. 2001. Predation by Gambusia holbrooki: a review of the literature. New South Wales National Parks and Wildlife Service.
Summary: A literature review that looks at both the effects of G. holbrooki on a range of different organisms and control options available. This document formed the background information for NSW NPWS (2003).
Mendoza, R.E.; Cudmore, B.; Orr, R.; Balderas, S.C.; Courtenay, W.R.; Osorio, P.K.; Mandrak, N.; Torres, P.A.; Damian, M.A.; Gallardo, C.E.; Sanguines, A.G.; Greene, G.; Lee, D.; Orbe-Mendoza, A.; Martinez, C.R.; and Arana, O.S. 2009. Trinational Risk Assessment Guidelines for Aquatic Alien Invasive Species. Commission for Environmental Cooperation. 393, rue St-Jacques Ouest, Bureau 200, Montr�al (Qu�bec), Canada. ISBN 978-2-923358-48-1.
Summary: In 1993, Canada, Mexico and the United States signed the North American Agreement on Environmental Cooperation (NAAEC) as a side agreement to the North American Free Trade Agreement (NAFTA). The NAAEC established the Commission for Environmental Cooperation (CEC) to help the Parties ensure that improved economic efficiency occurred simultaneously with trinational environmental cooperation. The NAAEC highlighted biodiversity as a key area for trinational cooperation. In 2001, the CEC adopted a resolution (Council Resolution 01-03), which created the Biodiversity Conservation Working Group (BCWG), a working group of high-level policy makers from Canada, Mexico and the United States. In 2003, the BCWG produced the �Strategic Plan for North American Cooperation in the Conservation of Biodiversity.� This strategy identified responding to threats, such as invasive species, as a priority action area. In 2004, the BCWG, recognizing the importance of prevention in addressing invasive species, agreed to work together to develop the draft CEC Risk Assessment Guidelines for Aquatic Alien Invasive Species (hereafter referred to as the Guidelines). These Guidelines will serve as a tool to North American resource managers who are evaluating whether or not to introduce a non-native species into a new ecosystem. Through this collaborative process, the BCWG has begun to implement its strategy as well as address an important trade and environment issue. With increased trade comes an increase in the potential for economic growth as well as biological invasion, by working to minimize the potential adverse impacts from trade, the CEC Parties are working to maximize the gains from trade while minimizing the environmental costs.
Available from: English version: http://www.cec.org/Storage/62/5516_07-64-CEC%20invasives%20risk%20guidelines-full-report_en.pdf [Accessed 15 June 2010]
French version: http://www.cec.org/Storage/62/5517_07-64-CEC%20invasives%20risk%20guidelines-full-report_fr.pdf [Accessed 15 June 2010]
Spanish version: http://www.cec.org/Storage/62/5518_07-64-CEC%20invasives%20risk%20guidelines-full-report_es.pdf [Accessed 15 June 2010].
New South Wales (NSW) National Parks and Wildlife Service 2003. NSW Threat Abatement Plan. Predation by Gambusia holbrooki � The Plague Minnow. NPWS. Hurstville, NSW.
Summary: Although this report refers to Gambusia holbrooki it is applicable to G. affinis as well.This management plan has been prepared in accordance with NSW legislative obligations for listed key threatening processes. It contains a review of the literature in regard to the biology, ecology, impacts and control of the species and includes proposed research and management actions. The plan also contains a model to predict the possible impact of Gambusia on NSW frog species.
Available from: http://www.nationalparks.nsw.gov.au/npws.nsf/Content/threat_abatement_plan_plague_minnow
Rowe, D.K and Graynoth, E, 2002. Lake Managers Handbook- Fish in New Zealand Lakes. Ministry for the Environment, Wellington.
Summary: Available from: http://www.mfe.govt.nz/publications/water/lm-fish-in-nz-lakes-jun02.pdf
Willis, K. and Ling, N. 2000. Sensitivites of mosquitofish and black mudfish to a piscicide: could rotenone be used to control mosquitofish in New Zealand waters? New Zealand Journal of Zoology 27: 85-91.
Summary: Has information on the possible use of the poison rotenone to control mosquitofish.
General information
Courtenay, W. R., Jr., and G. K. Meffe. 1989. Small fishes in strange places: a review of introduced poeciliids. Pages 319-331 in G. K. Meffe, and F. F. Snelson, Jr., editors. Ecology and evolution of livebearing fishes (Poeciliidae). Prentice Hall, Englewood Cliffs, NJ.
Duncan, Doug 2004. Novel application of a novel tool: Using a US endangered species act safe harbour agreement to reduce the use of mosquitofish. In Abstracts: 13th International Conference on Aquatic Invasive Species, September 20-24, 2004. Lynch West County Hotel, Ennis, County Clare, Ireland.
Summary: Report into the way that Gambusia affinis affects native fish.
Fishbase, 2003. Species profile Gambusia affinis Mosquitofish
Summary: FishBase is a global information system with all you ever wanted to know about fishes . FishBase on the web contains practically all fish species known to science. FishBase was developed at the WorldFish Center in collaboration with the Food and Agriculture Organization of the United Nations (FAO) and many other partners, and with support from the European Commission (EC). Since 2001 FishBase is supported by a consortium of seven research institutions. You can search on Search FishBase
This species profile is available from:
Freshwater Biodata Information System New Zealand (FBIS), 2005
Summary: The Freshwater Biodata Information System (FBIS) contains fish, algae, aquatic plant and invertebrate data and metadata gathered from New Zealand s freshwater streams, rivers and lakes. FBIS provides different ways to search for biodata: choose a predefined search from a list of common searches; use the map view to draw a box on a map and search for biodata; or create your own search for maximum search flexibility. FBIS is offered as a nationally available resource for the New Zealand public, institutions and companies who need access to a well-maintained long-term data repository.
Available from: https://secure.niwa.co.nz/fbis/validate.do?search=common [Accessed 5 August 2005]
Goodsell, J. A., and Kats, L. B. 1999. Effect of introduced mosquitofish on Pacific treefrogs and the role of alternative prey. Conservation Biology 13(4): 921-924.
Summary: Information on the impacts of mosquitofish.
Gophen M., Yehuda, Y., Malinkov, A., and Degani, G. 1998. Food composition of the fish community in Lake Agmon. Hydrobiologia 380: 49-57
Haas, R. C.; Thomas, M. V.; and Towns, G. L. 2003. An Assessment of the Potential Use of Gambusia for Mosquito Control in Michigan.Fisheries Technical Report 2003-2, Michigan Department of Natural Resources Fisheries Division.
Summary: A report recommending that Gambusia spp. Not be introduced to Michigan for mosquito control due to their negative effects on native biota.
Available from:http://www.michigandnr.com/PUBLICATIONS/PDFS/ifr/ifrlibra/technical/abstracts/2003-2abstract.pdf
ITIS (Integrated Taxonomic Information System), 2005. Online Database Gambusia affinis
Summary: An online database that provides taxonomic information, common names, synonyms and geographical jurisdiction of a species. In addition links are provided to retrieve biological records and collection information from the Global Biodiversity Information Facility (GBIF) Data Portal and bioscience articles from BioOne journals.
Available from: http://www.cbif.gc.ca/pls/itisca/taxastep?king=every&p_action=containing&taxa=Gambusia+affinis&p_format=&p_ifx=plglt&p_lang= [Accessed March 2005]
Keith, P. 2002. Revue des introductions de poissons et de crustac�s d�capodes d eau douce en Polyn�sie fran�aise. Bull. Fr. P�che Piscic, 364, 147-160.
Summary: Cet article fait le bilan des introductions d esp�ces dul�aquicoles en Polyn�sie fran�aise.
Keith P., Vigneux E. et G. Marquet. 2002. Atlas des poissons et crustac�s d�eau douce de la Polyn�sie fran�aise. Patrimoines naturels, (MNHN), 55 :1-175.
McCullough, Clint. 1998. The Voracious Mosquitofish: Gambusia or Damnbusia ? Forest & Bird, November 1998. New Zealand.
Summary: An article on the Gambusia in New Zealand.
McDowall, R. M. 1990. New Zealand Freshwater Fishes, A Natural History and Guide. Heinemann Reed.
Summary: A text book on the freshwater fishes of New Zealand.
McDowall, R. M. 2000. The Reed field guide to New Zealand freshwater fishes. Reed.
Summary: A useful guide to New Zealand freshwater fishes.
Myers, G. S. 1965. Gambusia, the fish destroyer. Australian Zoologist 13(2): 102.
Summary: An early article on the environmental impacts of Gambusia.
Nico, Leo and Pam Fuller, 2005, Gambusia affinis . Nonindigenous Aquatic Species Database, Gainesville, FL.
Summary: Available from: http://flgvwdmz014.er.usgs.gov/queries/FactSheet.asp?SpeciesID=845 [Accessed 20 January 2005]
Rader, Russell B.; Mills, M.D. and Belk, M.C. 2004. Complex interactions between native and invasive fish: The simultaneous effects of multiple negative interactions. In Abstracts: 13th International Conference on Auatic Invasive Species, September 20-24, 2004. Lynch West County Hotel, Ennis, County Clare, Ireland.
Summary: Report into the impacts of Gambusia affinis has on a native fish Lotichthys phlegethontis.
UN FAO. Fisheries information systems. (UN FAO).
Summary: Global distribution of Gambusia affinis
Available from: http://www.fao.org/scripts/acqintro/query/retrive.idc [Accessed: 17 July 2003]
The following 2 contacts offer information an advice on Gambusia affinis
USGS/BRD Nonindigenous Aquatic Species Program
Center for Aquatic Resources Studies 7920 NW 71st Street Gainesville, FL 32653
(352) 378-8181 x312
(352) 378-4956
National Institute of Water & Atmospheric Research Ltd.
National Institute of Water & Atmospheric Research Ltd. Address: PO Box 8602, Christchurch
Gambusia affinis
tes, Barkaleci, pez mosquito, Gambusino, western mosquitofish, Kounoupopsaro, guayacon mosquito, live-bearing tooth-carp, Western mosquitofish, Dai to ue, Obyknovennaya gambuziya, Mosquito fish, San hang ue, Koboldkärpfling, Gambusie, Topminnow, Isdang canal, Gambusia, Kadayashi, Gambuzia pospolita, Gambuzia, Gambuzija, Texaskärpfling, Silberkärpfling
Date assessed
Year published
Eicat category
Justification for EICAT assessment
Confidence rating
Mechanism(s) of maximum impact
Countries of most severe impact
Description of impacts
Recommended citation
(2024). Gambusia affinis. IUCN Environmental Impact Classification for Alien Taxa (EICAT).