''Xenotoca'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Goodeidae Goodeidae is a family of teleost fish endemic to Mexico and some areas of the United States. Many species are known as splitfins. This family contains about 50 species within 18 Genus, genera. The family is named after ichthyologist George Brow ...

from

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 ...

, where various species are found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma– Grande de Santiago, Panuco,

Cuitzeo Cuitzeo () is a municipality located in the north of the Mexican state of Michoacán. The municipal seat is the town of Cuitzeo del Porvenir It is located in a relatively flat depression around Lake Cuitzeo, a large, very shallow lake, which is i ...

and other basins of the

Mesa Central The Central Mexican Plateau, also known as the Mexican Altiplano (), is a large arid-to-semiarid plateau that occupies much of northern and central Mexico. Averaging above sea level, it extends from the United States border in the north to the T ...

. While no goodeid is a very common aquarium fish, the

redtail splitfin The redtail splitfin or redtail goodeid (''Xenotoca eiseni'') is a species of goodeid fish from the family Goodeidae and subfamily Goodeinae. Like other members of Goodeinae, the redtail splitfin is native to Mexico and a livebearer. However, t ...

(''X. eiseni''), is one of the most common aquarium goodeids; its bright colors offset its reputation for being aggressive towards and occasionally even killing tankmates. Similarly to ''X. eiseni'', two species described in 2016 have males with red-orange tails, but this feature is not shared by the remaining members of the genus. All ''Xenotoca'' species are relatively small, reaching up to in

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

Species

There are currently five recognized species in this genus, but two possibly

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and named. U ...

, tentatively referred to as ''Xenotoca

cf. The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...

melanosoma'' and ''Xenotoca cf. variata'', are known. Genetic work has shown that the genus, as currently defined, is not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

: The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

''X. variata'' is distantly related to the remaining, which could eventually be reallocated to their own genus. Phylogenic research by Shane Webb showed that the closest relative of ''X. variata'' is the butterfly goodeid, ''Ameca splendens''. * ''

Xenotoca doadrioi ''Xenotoca doadrioi'' or San Marcos redtail splitfin is a bony fish species in the goodeid family. Until 2016 it was considered to be a variant of the redtail goodeid, ''X. eiseni'', sometimes referred to as the San Marcos variant. A 2016 stu ...

'' Domínguez-Domínguez, Bernal-Zuñiga & Piller, 2016 (San Marcos redtail splitfin) * ''

Xenotoca eiseni ''Xenotoca'' is a genus of fish in the family (biology), family Goodeidae from Mexico, where various species are found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma River, Lerma–Grande de Santiago River, G ...

'' ( Rutter, 1896) (Redtail splitfin) * ''

Xenotoca lyonsi ''Xenotoca lyonsi'', the Tamazula redtail splitfin, is a bony fish species in the goodeid family. Until 2016 it was considered to be a variant of the redtail goodeid, ''X. eiseni''. A 2016 study by Omar Dominguez-Dominguez, ''et al''. split th ...

'' Domínguez-Domínguez, Bernal-Zuñiga & Piller, 2016 * ''

Xenotoca melanosoma ''Xenotoca'' is a genus of fish in the family Goodeidae from Mexico, where various species are found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma– Grande de Santiago, Panuco, Cuitzeo and other basins of ...

'' Fitzsimons, 1972 (Black splitfin) * ''

Xenotoca variata ''Xenotoca'' is a genus of fish in the family Goodeidae from Mexico, where various species are found in a wide range of habitats, from rivers and creeks to pools and lakes, in the Lerma– Grande de Santiago, Panuco, Cuitzeo and other basins of ...

'' ( T. H. Bean, 1887) (Jeweled splitfin)

References

Endemic fish of Mexico Freshwater fish genera Freshwater fish of Mexico Goodeinae Taxa named by Carl Leavitt Hubbs Ray-finned fish genera Mexican Plateau {{Cyprinodontiformes-stub