Aphyocharax is a genus of small, slender tetras in the family Characidae, native to slow-moving streams, floodplains, and quiet backwaters across South America — the atlas's coverage spans Brazil, Paraguay, Argentina, Bolivia, Colombia, Peru, Venezuela, and Ecuador. Most species are only a few centimeters long, with a laterally compressed, translucent body and, in several species, distinctly colored fins that give the genus its common thread — active, open-water schooling fish that move in tight, fast groups rather than hugging cover.
The genus's best-known aquarium export is the bloodfin tetra (Aphyocharax anisitsi), one of the longest-established tropical fish in the hobby, valued for its peaceful schooling temperament, hardiness, and tolerance of cooler water than most tetras. Related species carry the same bloodfin pattern into the trade in smaller numbers, including the flametail tetra (A. erythrurus), Natterer's bloodfin (A. nattereri), and redflank bloodfin (A. rathbuni). Aphyocharax are undemanding community fish, best kept in groups in planted tanks with steady water quality; conservation status across the genus is generally favorable, though a couple of species carry a Vulnerable rating.