This group of freshwater fish is one of the largest and most diverse, containing over 1300 species. Most are found in the Americas, with the rest mainly in Africa. They are noted for having teeth, having an adipose fin, and being egg-scatterers. Most Characins are omnivorous, although some are herbivorous and carnivorous.

Tetras, the popular aquarium fish, are a member of this group, as are Piranhas. Other members include hatchetfish and pencilfish.