The Chiapas swordtail or upland swordtail (''Xiphophorus alvarezi'') is a species of livebearing

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 ...

of family

Poeciliidae The Poeciliidae are a family of freshwater fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, molly, platy, and swordtail. The original distribution of the family was t ...

, and

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Xiphophorus ''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. The many ''Xiphophorus'' species are all known as platyfish (or platies) and ...

''. It is, therefore, in the same genus as the common platy and the

swordtail ''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. The many ''Xiphophorus'' species are all known as platyfish (or platies) and s ...

. The Chiapas swordtail was discovered and first described by Donn E. Rosen in 1960, along with four other species of ''Xiphophorus''.

Description

Male Chipas swordtails attain up to in length. They have an overall body colour of orange market with pearlescent white spots and with green. The lower part of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

extends into a long "sword" which is bright green edged with black. The females are drabber, however, they may also have some orange markings on their sides. Females are smaller than males and reach a maximum length of .

Distribution

The Chiapas swordtail is restricted to eastern

Chiapas Chiapas (; Tzotzil language, Tzotzil and Tzeltal language, Tzeltal: ''Chyapas'' ), officially the Free and Sovereign State of Chiapas ( es, Estado Libre y Soberano de Chiapas), is one of the states that make up the Political divisions of Mexico, ...

in Mexico and adjacent parts of

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

Habitat and biology

The Chiapas swordtail is found in rivers with fast flows. Their preferred habitat is shallow, clear pools which have a moderate current where there are rocks covered with algae. They graze algae off the rocks. They are

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

and females can give birth to 20-801 young after a

gestation period In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it ...

of 24-30 days.

Species description and etymology

The Chiaps swordtail was described as ''Xiphophorus helleri alvarezi'' by Donn E. Rosen in 1960 with the type locality given as Río Santo Domingo, a tributary of the

Río Jatate Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a ...

of the

Río Usumacinta The Usumacinta River (; named after the howler monkey) is a river in southeastern Mexico and northwestern Guatemala. It is formed by the junction of the Pasión River, which arises in the Sierra de Santa Cruz (in Guatemala) and the Salinas R ...

system in Chiapas. This fish's specific name honours the

Mexican Mexican may refer to: Mexico and its culture *Being related to, from, or connected to the country of Mexico, in North America ** People *** Mexicans, inhabitants of the country Mexico and their descendants *** Mexica, ancient indigenous people ...

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, 33,400 species of fish had been described as of Octobe ...

José Álvarez del Villar José is a predominantly Spanish and Portuguese form of the given name Joseph. While spelled alike, this name is pronounced differently in each language: Spanish ; Portuguese (or ). In French, the name ''José'', pronounced , is an old vernacu ...

(1903-1986) who showed this species to Rosen.

Aquarium

Ideal, suitable conditions for Chiapas swordtails include a water temperature of around 25–28 °C. These are ''benthopelagic'' fish. Water pH should range from 7.2 to 8.1. They are quite resilient fish. They are often found in fast-flowing rivers. In nature, schools of more females than males are common, and enjoy dense aquatic foliage to give birth in. They reproduce quickly and prefer live foods and aquatic plants.

References

* http://www.fishbase.org/Summary/SpeciesSummary.php?ID=47328 * http://www.aquaticcommunity.com/fish/uplandswordtail.php {{Taxonbar, from=Q3494640 Live-bearing fish Ovoviviparous fish Xiphophorus Fish of Guatemala Freshwater fish of Mexico Taxa named by Donn Eric Rosen Fish described in 1960