A piranha (, or ; Portuguese: [piˈɾɐ̃ɲɐ]) is any of a number of freshwater fish species in the subfamily Serrasalminae, of the family Serrasalmidae, in the order Characiformes. These fish inhabit South American rivers, floodplains, lakes and reservoirs. Although often described as extremely predatory and mainly feeding on fish, their dietary habits vary extensively, and they will also take plant material, leading to their classification as omnivorous.