Priapichthys is a genus of small livebearing fish in the family Poeciliidae, native to lowland and foothill streams in Panama, Costa Rica, Nicaragua, and Colombia. The atlas covers 7 species ranging from about 1 in up to 2.5 in. Several carry the common name "toothcarp," a term that gets applied loosely across egg-laying killifish and livebearing poeciliids alike, but Priapichthys is a true livebearer: males fertilize females internally via a modified anal fin, the gonopodium, and females give birth to free-swimming young rather than laying eggs. The genus's range sits right across the Central American land bridge into northern South America, a biogeographic crossroads reflected in several narrowly distributed species named for individual river drainages, such as P. chocoensis (Choco toothcarp) and P. darienensis (Capetí toothcarp).
Priapichthys is not a mainstream aquarium genus; it is of far more interest to livebearer specialists and biogeographers than to the general trade, with species such as P. annectens (orange finned toothcarp) and P. panamensis (Panama toothcarp) rarely available outside dedicated hobbyist networks. The conservation picture is uneven: most assessed species sit at Least Concern, but one, listed here as CARES-flagged, is Critically Endangered, underscoring how a restricted stream range in Central America can leave an otherwise unremarkable small livebearer vulnerable to habitat degradation.