File:Flagtail Characin (Semaprochilodus taeniurus) (3420299646).jpg

Semaprochilodus are one of the most common and widespread shoaling fish found in South America. Over a dozen species have been described but most are never imported. They are used as food fish in their native countries.

Semaprochilodus taeniurus is also sold as the Silver Prochilodus or Fei Feng. Along with some congeners, it is commonly known as the Jaraqui in Brazil. It is an interesting species both ecologically and biologically. In nature it migrates over large distances in huge shoals according to the season, feeding on organic detritus. This detritivorous feeding habit and migratory nature plays an important part in maintaining ecosystem structure and dynamics as it processes large amounts of organic sediments as it sifts for food. It also has two stomachs, one of which is filled with mud to aid digestion.

It migrates twice a year. The first event is a spawning migration at the start of the wet season, when the fish move from nutrient-poor black and clear water tributaries and streams into the more turbulent white (silt-laden) waters near the heads of rivers to spawn. They may travel several hundred kilometres and can even be seen leaping through rapids in a similar fashion to salmon. Post-spawning the fertilised eggs drift downstream and into the nutrient rich floodplains. These act as the perfect "nurseries" for the fry to feed and grow.