Pinktail Chalceus

Found singly or in small schools, near the surface of fresh well oxygenated waters, in rivers and river basins, very active, always jumping and moving around.
Widespread South America

Same family as Piranha's

Piranha's have a fearsome reputation (because of James bond 007) as a voracious predator that can strip flesh off bones in minutes, although they have razor sharp teeth they are in fact quite timid scavengers.