abstract:Pacu () is a common name used to refer to several common species of omnivorous South American freshwater fish that are related to the piranha. Pacu and piranha do not have similar teeth, the main difference being jaw alignment; piranha have pointed, razor-sharp teeth in a pronounced underbite, whereas pacu have squarer, straighter teeth, like a human, and a less severe underbite, or a slight overbite.
Triangular blue pacu, iridescent, fiery-finned pirupatanga and streamlined yellow dorado gather in shoals or slip effortlessly between fallen tree trunks, eyeing the ungainly human intruders warily.