A piranha or piraƱa, a member of family Serrasalmidae, or a member of the subfamily Serrasalminae within the tetra family, Characidae in order Characiformes, is a freshwater fish that inhabits 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.