As far as I know that aspect of Piranhas is overhyped in popular culture, and they're pretty much omnivores, hunting fresh prey, scavenging on carcasses and eating plant matter. Agreed though that naming it after a pure scavenger would make more sense.
> Although generally described as highly predatory and primarily feeding on fish, piranha diets vary extensively, leading to their classification as omnivorous. In addition to fish (occasionally even their own species), documented food items for piranhas include other vertebrates (mammals, birds, reptiles), invertebrates (insects, crustaceans), fruits, seeds, leaves and detritus. The diet often shifts with age and size.
> In another study of more than 250 Serrasalmus rhombeus at Ji-Paraná (Machado) River, 75% to 81% (depending on season) of the stomach content was fish, but about 10% was fruits or seeds
