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Gambusia affinis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII CYPRINODONTIFORMES POECILIIDAE

Scientific Name: Gambusia affinis
Species Authority: (Baird & Girard, 1853)
Common Name(s):
English Western Mosquitofish
Synonym(s):
Heterandria affinis Baird & Girard, 1853

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2013
Date Assessed: 2012-02-03
Assessor(s): NatureServe
Reviewer(s): Smith, K. & Darwall, W.R.T.
Facilitator/Compiler(s): Hammerson, G.A. & Ormes, M.
Justification:
Listed as Least Concern in view of the large extent of occurrence, large number of subpopulations, large population size, apparently stable trend, and lack of major threats.

Geographic Range [top]

Range Description: This species is native to most of south-central United States, north to Indiana and Illinois, west to Texas, south to southern Mexico, east to Mobile River system. Populations in the drainages of the Chattahoochee and Savannah rivers (Lydeard and Wooten 1991) possibly are native (Page and Burr 2011). See Walters and Freeman (2000) for information on the distribution of G. affinis and G. holbrooki in the Conasauga River system, where G. affinisi is widespread and native and G. holbrooki is apparently introduced and expanding its range. This fish is widely introduced in the western United States and throughout the world.

Lynch (1992) reported that five or six populations from Georgia, Illinois, Tennessee and Texas were used for most introductions nationwide and worldwide. Within the United States, sources from Illinois, Tennessee and Texas were used to establish mosquitofish in the western half of the country. Therefore, most if not all populations in the western United States are G. affinis.
Countries:
Native:
Mexico; United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is represented by a large number of occurrences (subpopulations).

"Possibly the single most abundant freshwater fish in the world" (Minckley et al. 1991).

Trend over the past 10 years or three generations is uncertain but likely relatively stable.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Habitat includes river channels, margins, backwaters; springs, marshes, and artificial habitats of all kinds (Minckley et al. 1991). Often this species occurs in shallow, often stagnant, ponds and the shallow edges of lakes and streams where predatory fishes are largely absent and temperatures are high. It is most abundant in shallow water with thick vegetation (Hubbs 1971). It also occurs in brackish sloughs and coastal saltwater habitats (Tabb and Manning 1961, Odum 1971). This fish is more tolerant of pollution than are most other fishes (Lewis 1970, Kushlan 1974). It tolerates dissolved oxygen levels as low as 0.18 mg/L (Ahuja 1964) but cannot tolerate extreme cold; temperature apparently limits the range northward (Hubbs 1971). However, some populations are known to overwinter under ice in Indiana and Illinois (Krumholz 1944).
Systems: Freshwater

Use and Trade [top]

Use and Trade: The species has been widely introduced worldwide as a form of biological mosquito control.

Threats [top]

Major Threat(s): No major threats are known.

Conservation Actions [top]

Conservation Actions: Currently, this species is of relatively low conservation concern and does not require significant additional protection or major management, monitoring, or research action.

Citation: NatureServe 2013. Gambusia affinis. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 17 September 2014.
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