6-550: The San Marcos gambusia ( Gambusia georgei ) is a likely extinct species of Gambusia from the family Poeciliidae that was found only in the San Marcos Springs of Central Texas . The fish has not been seen since 1983. The specific name of this fish honors the American ichthyologist George S. Myers (1905–1985). The San Marcos gambusia was typically less than 1.6 inches (4 cm) in length. It had
12-603: A 0.6-mile (1-km) stretch of the headwaters of the San Marcos River . They appeared to need clean and clear water, with little temperature variability. They apparently also preferred shallow, quiet water, along with partial shade. As of 1969, the population was less than 1,000 individuals. The species was threatened by reduced spring flows and pollution, including sprayed herbicide along the river and introduced fish ( Gambusia affinis ) and plants ( Colocasia esculenta ). There have been no specimen sightings since 1983 and
18-403: A consequence, they have been introduced widely outside their native range, and frequently become invasive , threatening local species. G. affinis and G. holbrooki are now established in many parts of the world and are likely to continue to spread as climatic conditions change. They are only occasionally kept in aquariums, due to their relative lack of color and the highly aggressive nature of
24-440: A dark body with a slight blue tint, although the median fins were lemon yellow. The scales were strongly crosshatched, and the dorsal fin had a dark stripe along its edge. The species’ exact diet is not known, but other poeciliids typically eat insect larvae and other small invertebrates . The fish were live bearing and were known to give birth to a few dozen young at a time. The San Marcos gambusia has only been identified in
30-878: The Cuban term, "Gambusino", which means "free-lance miner". The type species is the Cuban gambusia , G. punctata . The greatest species richness is in Mexico, Texas , and the Greater Antilles , but species are also found elsewhere in the eastern and southern United States , the Bahamas , Central America, and Colombia . Gambusia species are often called topminnows, or simply gambusias; they are also known as mosquitofish, which, however, refers more specifically to two species, G. affinis and G. holbrooki , which are often introduced into ponds to eat mosquito larvae. As
36-568: Was proposed to be delisted from the Endangered Species Act in 2021. The US Fish and Wildlife Service delisted the species effective November 16, 2023. Gambusia Gambusia is a large genus of viviparous fish in the family Poeciliidae (order Cyprinodontiformes ). Gambusia contains over 40 species, most of which are principally found in freshwater habitats, though some species may also be found in brackish or saltwater habitats. The genus Gambusia comes from
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