Pseudoxiphophorus is a genus of livebearing fish in the family Poeciliidae, native to streams and rivers of southern Mexico and Central America, including Guatemala, Honduras, Belize, and Nicaragua. The atlas covers 7 species ranging from about 2.5 in up to 6 in, making this a somewhat larger-bodied genus than many other livebearers in the same family. As poeciliids, they reproduce by internal fertilization through a male gonopodium, with females bearing live, free-swimming young. Several species carry "toothcarp" common names, such as the Sebol toothcarp (P. cataractae) and Usumacinta toothcarp (P. obliquus), tied to the specific river drainage each is best known from.
The genus attracts more interest from livebearer specialists and regional-endemic collectors than from the mainstream aquarium trade, with named species including the blue spotted Guatemala toothcarp (P. anzuetoi), the twospot livebearer (P. bimaculatus), and the barred killifish (P. jonesii, despite the common name, a true livebearer rather than an egg-laying killifish). Conservation status leans toward Least Concern for most species, but two are listed as Vulnerable and the genus carries two species flagged under the CARES conservation program, pointing to real pressure on some of the more range-restricted populations across its Central American distribution.