The widemouth gambusia (''Gambusia eurystoma'') is a species of fish in the family Poeciliidae of the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Cyprinodontiformes. It is endemic to Mexico, specifically to the Baños del Azufre ( Grijalva River basin) near

Teapa Teapa Municipality is a municipality in Tabasco in south-eastern Mexico. Its name comes from the Nahuatl words "Tetl'' and ''apan", which mean "river over stones" or "stone's river". It refers to one of the rivers that crosses the town. The muni ...

, Tabasco. The Baños del Azufre are sulfidic springs that contain high concentrations of toxic

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...

(). This prevents most animals from living in them; the only other fish found in the toxic sections of Baños del Azufre is the

sulphur molly The sulphur molly (''Poecilia sulphuraria''), locally known as ''molly del Teapa'', is an endangered species of fish in the family Poeciliidae. It is endemic to Mexico, specifically to the Baños del Azufre (Grijalva River basin) near Teapa, Ta ...

(''Poecilia sulphuraria'').Tobler; Riesch; García de León; Schlupp; & Plath (2008). ''Two endemic and endangered fishes, Poecilia sulphuraria (Alvarez, 1948) and Gambusia eurystoma Miller, 1975 (Poeciliidae, Teleostei) as only survivors in a small sulphidic habitat.'' Journal of Fish Biology 72: 523–533. This species reaches a maximum overall length around . Little is known about ''G. eurystoma'', but the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

classifies it as Critically Endangered on the basis of a very small (less than 250 individuals) and rapidly falling population and a small, localized, and diminishing geographical distribution.

References

* {{Taxonbar, from=Q2136543 Gambusia Freshwater fish of Mexico Endemic fish of Mexico Fish described in 1975 Ovoviviparous fish Live-bearing fish