Gambusia affinis

Gambusia affinis
Female
Male
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cyprinodontiformes
Family:	Poeciliidae
Genus:	Gambusia
Species:	G. affinis
Binomial name
Gambusia affinis (Baird and Girard, 1853)

The mosquitofish (Gambusia affinis) is a species of freshwater fish, also commonly, if ambiguously, known by its generic name, gambusia. It is sometimes called the western mosquitofish, to distinguish it from the eastern mosquitofish (G. holbrooki). It is a member of the family Poeciliidae of order Cyprinodontiformes. The genus name Gambusia is derived from the Cuban Spanish term gambusino, meaning "useless".^[2]

Description

Mosquitofish are small and stout, dull grey, and quite robust, with a rounded tail and a terminal and upward-pointing mouth adapted for feeding at the water's surface. In these features and their small size they resemble the tropical guppies, which belong to the same taxonomic family. Sexual dimorphism is pronounced; mature females reach a maximum overall length of 7 centimeters (2.8 in), while males reach only 4 centimeters (1.6 in). Sexual dimorphism is also seen in the physiological structures of the body. The anal fins on adult females resemble the dorsal fins, while the anal fins of adult males are pointed. This pointed fin, referred to as a gonopodium, is used to deposit sperm inside the female.^{[citation needed]} Other similar species of G. affinis include Poecilia latipinna, Poecilia reticulata, Xiphophorus maculatus, and is commonly misconceived as the eastern mosquitofish.^[3][4]

Naming and Taxonomy

The common name of the Gambusia affinis is the mosquitofish. This name is derived from the fact that it eats large amounts of mosquito larve.^[4]

Habitat

Mosquitofish are indigenous to the watershed of the Gulf of Mexico, where they feed readily on the aquatic larval and pupal stages of mosquitoes. Mosquitofish can survive relatively ihospitable environments, and are resilient to low oxygen concentrations, high salt concentrations (up to twice that of sea water), and temperatures up to 42° Celsius (for short periods).^[3] For these reasons, this species may now be the most widespread freshwater fish in the world, having been introduced as a biocontrol to tropical and temperate countries in both hemispheres, and then spreading further both naturally and through even further introductions. The majority of these introductions were ill-advised; in most countries where mosquitofish have been introduced, endemic fish species were proven to already provide maximal mosquito control, and the introduction of mosquitofish has been both unnecessary and highly damaging to endemic fish and other endemic aquatic life.^[5] In Australia, G. holbrooki has caused great damage to indigenous fish and frog species. For example, it is considered responsible for the extinction of rainbowfish in subtropical streams around Brisbane. However, in some areas, introduction of mosquitofish did help in eradicating malaria, for example, in South America and in the south of Russia and Ukraine in the 1920s–1950s,^[6] particularly at the Black Sea coast near Sochi, Russia.^[7] A monument to the fish was raised there in 2010 in recognition of that fact.^[8][9]

Diet

Mosquito Larvae.

The diet of mosquitofish mostly consists of zooplankton, small insects and insect larvae, and detritus material. Mosquitofish feed on mosquito larvae at all stages of life. Adult female mosquitofish can consume in one day hundreds of mosquito larvae.^[4] Maximum consumption rate in a day by one mosquitofish has been observed to be from 42%-167% of its own body weight.^[10]

Environmental Impacts

Mosquitofish were intentionally introduced in many areas with large mosquito populations so that they might decrease the population of mosquitoes by eating the mosquito larvae.^[4] Their presence, however, has harmed some of the native species in these areas. Mosquitofish have been known to kill or injure other small fish by their aggressive behaviour and otherwise harm them through competition.^[10] Mosquitofish are now considered just slightly better at eating mosquitoes than at destroying other aquatic species.^[3]

Reproduction

Female mosquitofish can reach sexual maturity in only six to eight weeks, and they may bear three to four broods in a single season. The first may number only a dozen, but later broods expand to 60 to 100 offspring. Females store sperm in their reproductive tracts for up to two months and give birth to live offspring. Live-bearing gives their young a much higher survival rate than in most species of egg-laying fish, which typically suffer from egg predation.

Under favorable conditions, mosquitofish live two to three years. Estimates of their breeding potential have therefore demonstrated an incredible ability for this species to multiply and dominate new habitats into which they have been introduced. Their success in a new environment is almost guaranteed by their rapid maturation, by breeding several times a year, and producing broods of around 50 advanced live young. Individual populations have been recorded expanding from 7,000 to 120,000 in five months.^{[citation needed]}

See also

• Mosquitofish in Australia

References

1. ^ Whiteside, Bobby; Bonner, Timothy; Thomas, Chad; Whiteside, Carolyn. "Gambusia affinis western mosquitofish". Texas State University. http://www.bio.txstate.edu/~tbonner/txfishes/gambusia%20affinis.htm. Retrieved 25 October 2011. 
2. ^ (Wallace 1990, p. 175)
3. ^ ^{a b c} "Gambusia affinis (fish)". Global Invasive Species Database. http://www.issg.org/database/species/ecology.asp?fr=1&si=126. Retrieved 21 October 2011. 
4. ^ ^{a b c d} Masterson, J. "Gambusia affinis". Smithsonian Institution. http://www.sms.si.edu/irlspec/Gambusia_affinis.htm. Retrieved 21 October 2011. 
5. ^ "Гамбузия". Большая советская энциклопедия. Академике. 2000-2010. http://dic.academic.ru/dic.nsf/bse/77453/%D0%93%D0%B0%D0%BC%D0%B1%D1%83%D0%B7%D0%B8%D1%8F. Retrieved 23 October 2011 (in Russian). 
6. ^ (Vinogradova 2000, p. 187)
7. ^ Ильин, Иван. "История человека – история города Сочи" (in Russian). Объявления Сочи: История человека – история города Сочи / 135 лет со дня рождения Сергея Юрьевича Соколова. http://www.irrsochi.ru/news/121.html. Retrieved 8 November 2011. 
8. ^ "В Сочи установлен памятник рыбке, спасшей местность от малярии" (in Russian) (Press release). Кавказский узел. июнь 26 2010. http://www.kavkaz-uzel.ru/articles/170779/. Retrieved 8 November 2011. 
9. ^ "Врачу, спасшему Сочи от малярии, поставят памятник" (in Russian) (Press release). ФедералПресс. 22 Июля 2010 (четверг). http://fedpress.ru/federal/polit/society/id_193168.html. Retrieved 8 November 2011. 
10. ^ ^{a b} Nico, Leo; Fuller, Pam; Jacobs, Greg; Cannister, Matt (19 August 2009). "Gambusia affinis". USGS. http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=846. Retrieved 25 October 2011. 

Bibliography

• Vinogradova, Elena Borisovna (2000). Culex pipiens pipiens mosquitoes: taxonomy, distribution, ecology, physiology, genetic, applied importance and control. Pensoft Publishers. ISBN 9789546421036. http://books.google.com/books?id=770ImWlj3PsC&pg=PA187. Retrieved 29 April 2011. 
• Wallus, Robert; Simon, T.P. (1990). Reproductive Biology and Early Life History of Fishes in the Ohio River Drainage. Taylor & Francis. ISBN 0849319218. 

External links

• FishBase: Froese, Rainer, and Daniel Pauly, eds. (2006). "Gambusia affinis" in FishBase. April 2006 version.
• ITIS: Gambusia affinis
• Using Mosquitofish to Control Mosquito Larvae at About.com
• Gambusia Control Homepage