Semaprochilodus

The flagtail prochilodus, Semaprochilodus insignis, is a large shoaling characin from Ecuador, Peru, Colombia, Guyana and Brazil. Known with some congeners as the jaraqui in Brazil, it migrates over large distances in huge shoals and feeds on organic detritus, using one of its two stomachs, filled with mud, to aid digestion. It is aggressive towards its own kind in small numbers but can be kept in groups of six or more in larger tanks.

The flagtail characin, Semaprochilodus taeniurus, is a large shoaling fish from the central Amazon basin in Brazil, growing to around 30 cm. Also sold as the silver prochilodus or fei feng, it migrates twice a year in huge shoals, moving into white waters to spawn at the start of the wet season and feeding mostly in the floodplains. It is aggressive towards its own kind in small numbers but can be kept in groups of six or more in larger tanks.