The marbled swordtail (''Xiphophorus meyeri'') is a species of

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

in the family

Poeciliidae Poeciliidae are a Family (biology), family of freshwater ray-finned fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, Poecilia, molly, Platy (fish), platy, and Green swo ...

. It was

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Rio Salado system (itself a part of the

Rio Grande The Rio Grande ( or ) in the United States or the Río Bravo (del Norte) in Mexico (), also known as Tó Ba'áadi in Navajo language, Navajo, is one of the principal rivers (along with the Colorado River) in the Southwestern United States a ...

basin) in

Coahuila Coahuila, formally Coahuila de Zaragoza, officially the Free and Sovereign State of Coahuila de Zaragoza, is one of the 31 states of Mexico. The largest city and State Capital is the city of Saltillo; the second largest is Torreón and the thi ...

, northeastern

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. It was restricted to springs, connected creeks and pools in waters with a pH slightly above neutral and temperatures of , with captive studies indicating that the optimum temperature is around . The marbled swordtail is considered

extinct in the wild A species that is extinct in the wild (EW) is one that has been categorized by the International Union for Conservation of Nature as only consisting of living members kept in captivity or as a naturalized population outside its historic range ...

by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

with the last wild record in 1997, meaning that it survives only in captivity. Captive populations are maintained at the ''Xiphophorus'' Genetic Stock Center,

Texas State University Texas State University (TXST) is a public university, public research university with its main campus in San Marcos, Texas, United States, and another campus in Round Rock, Texas, Round Rock. Since its establishment in 1899, the university has ...

, United States, and by XNP conservation project members, which include public aquariums, universities and private aquarists in several European countries and the United States. The marbled swordtail shares the title as northernmost naturally distributed ''

Xiphophorus ''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order (biology), order Cyprinodontiformes, native to Mexico and northern Central America. ''Xiphophorus'' species can be divided into three groups based ...

'' with the closely related

Monterrey platyfish The Monterrey platyfish (''Xiphophorus couchianus'') is a species of freshwater fish in family Poecilidae. A live-bearer, it was native to a very small section of the San Juan River system (itself part of the Rio Grande basin) in the vicinity ...

(''X. couchianus'') and

northern platyfish The northern platyfish (''Xiphophorus gordoni'') is a small, endangered species of fish in the family Poeciliidae. It is endemic to the vicinity of Cuatro Ciénegas in the Mexican state of Coahuila. It is restricted to hot-spring heated ditches ...

(''X. gordoni''). The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

of this species honours the

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Manfred K. Meyer ''Manfred: A dramatic poem'' is a closet drama written in 1816–1817 by Lord Byron. It contains supernatural elements, in keeping with the popularity of the ghost story in England at the time. It is a typical example of Gothic fiction. Byro ...

References

{{Taxonbar, from=Q2243165 Freshwater fish of Mexico Live-bearing fish Xiphophorus Taxa named by Manfred Schartl Taxa named by Johannes Horst Schröder Fish described in 1988 Taxonomy articles created by Polbot