Alfaro is a small genus of livebearers in family Poeciliidae, the same live-bearing family that gives the hobby guppies, mollies, and platies. The genus is native to Central America, found in rivers and streams across Nicaragua, Costa Rica, Guatemala, Honduras, and Panama. The atlas covers 2 species, 3 in as adults, and both share the distinctive shape that earns the genus its common name 'knife livebearers' - a slim, laterally compressed profile with a sharply keeled belly, an adaptation thought to help the fish glide near the surface and evade predators from below.
Alfaro cultratus is the species most likely to reach specialist livebearer keepers, prized less for bright color than for its sleek, torpedo shape and calm, schooling temperament - a livebearer for aquarists who want something other than the usual guppy or platy silhouette. Alfaro huberi is far less established in the trade. Both species are assessed as Least Concern, and Central America's Alfaro populations do not currently carry the conservation pressure seen in some of the region's other livebearer genera.