The Monterrey platyfish (''Xiphophorus couchianus'') is a species of

freshwater fish Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 1.05%. These environments differ from marine conditions in many ways, especially the difference in levels of s ...

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Poecilidae. A live-bearer, it was native to a very small section of the San Juan River system (itself part of the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

basin) in the vicinity of the city of

Monterrey Monterrey ( , ) is the capital and largest city of the northeastern state of Nuevo León, Mexico, and the third largest city in Mexico behind Guadalajara and Mexico City. Located at the foothills of the Sierra Madre Oriental, the city is anchor ...

, Mexico. 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 ...

refers to the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

soldier and naturalist

Darius N. Couch Darius Nash Couch (July 23, 1822 – February 12, 1897) was an American soldier, businessman, and naturalist. He served as a career U.S. Army officer during the Mexican–American War, the Second Seminole War, and as a general officer in the Uni ...

(1822–1897) who collected the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

on a self financed expedition to Mexico.

Appearance

The Monterrey platyfish is a dull-colored fish, appearing not unlike a female guppy. Another form, sometimes referred to as ''X.

aff. ''Species affinis'' (commonly abbreviated to: ''sp.'', ''aff.'', or ''affin.'') is taxonomic terminology in zoology and botany. In open nomenclature it indicates that available material or evidence suggests that the proposed species is related to, h ...

couchianus'', was discovered in Apodaca, central Monterrey, in 1983. It has large black blotching, unlike the typical, unspotted form from the Huasteca Canyon. Whether the Apodaca form represents a separate species is presently unclear.

Sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

is moderate, the male Monterrey platyfish growing to a maximum overall length of and the female .

Conservation

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 ...

lists the Monterrey platyfish as "

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 known only by living members kept in captivity or as a naturalized population outside its historic range due ...

". Although once found more widely in the region of Monterrey, populations have been lost to

urban sprawl Urban sprawl (also known as suburban sprawl or urban encroachment) is defined as "the spreading of urban developments (such as houses and shopping centers) on undeveloped land near a city." Urban sprawl has been described as the unrestricted growt ...

, with water habitats either drying up (due to land reclamation and water extraction) or being heavily polluted.

Introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...

is another threat. "Safety populations" are maintained in captivity by the Centro de Resguardo para Peces en Peligro de Extinción at Universidad Autónoma de Nuevo León, Mexico (maintaining both the typical form and ''X. aff. couchianus''), ''Xiphophorus'' Genetic Stock Center at Texas State University, United States (maintaining typical form), via the American Livebearer Association that mostly includes private aquarists in the United States (maintaining typical form), and by XNP conservation project members, which include public aquariums, universities and private aquarists in several European countries and the United States (maintaining typical form). The species has proven harder to maintain in captivity than most ''Xiphophorus'' species. The Monterrey platyfish shares the title as northernmost naturally distributed ''Xiphophorus'' with the closely related

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'') and

marbled swordtail The marbled swordtail (''Xiphophorus meyeri'') is a species of freshwater fish in the family Poeciliidae. It was endemic to the Rio Salado system (itself a part of the Rio Grande basin) in Coahuila, northeastern Mexico. It was restricted to spri ...

(''X. meyeri''), which are two species that also are restricted to northeastern Mexico and seriously threatened.

References

* {{Taxonbar, from=Q2170401 Freshwater fish of Mexico Xiphophorus Fish described in 1859 Taxa named by Charles Frédéric Girard IUCN Red List extinct in the wild species