What is "pyrrhulina"

Pyrrhulina is a genus of freshwater fishes found in tropical South America. Several of these species are popular aquarium fish.

Pyrrhulina is closely related to Copeina and Copella, although it is distinguished from the former by having only one row of teeth (Copeina spp. have two). When the genus Copella was established, many species were removed from the genus Pyrrhulina and placed there, because differences in the maxillary bones in the males had been detected. Copella species are slimmer and more elongated than those species that remained in the genus Pyrrhulina.