The yellow swordtail (Xiphophorus clemenciae) is a species of freshwater
fish in the family
Poeciliidae.[2] It is
endemic to the upper
Coatzacoalcos River basin in southern
Mexico.[3] It is typically found in brooks and streams with slow current; it is less frequent in areas with strong current.[2] The yellow swordtail is considered a
threatened species by Mexican authorities.[4] It reaches up to 5.1 cm (2.0 in) in
standard length.[2]
Unusually, the yellow swordtail appears to be the result of
hybrid speciation, and its ancestors a
platy species and a
swordtail species.[3][5] The
southern mountain swordtail (X. monticolus), which is found further south in the Coatzacoalcos River basin than the yellow swordtail, is the result of a similar event.[3]
The fish is named in honor of Álvarez’ wife Clemencia, whose help and advice made it possible for him to devote himself to the pursuit of his scientific research.[6]
^Ceballos, G.; E.D. Pardo; L.M Estévez; H.E. Pérez, eds. (2016). Los peces dulceacuícolas de México en peligro de extinción. Fondo de Cultura Económic. p. 279.
ISBN978-607-16-4087-1.