Pygocentrus

Has been recorded from major river channels, smaller tributaries, and floodplain lakes, many of which comprise acidic, mineral-poor blackwater environments with brownish, tannin-stained water, although it has been observed to inhabit clear waters as well. Many of its habitats lie within the Venezuelan and Colombian llanos, a vast, highly biodiverse system of tropical savannah grasslands, seasonally-flooded plains and forests covering an area measuring almost 600,000 square kilo...

Famed as a rapacious predator capable of rapidly stripping flesh from bone and a danger to any animal entering its native waters, P. nattereri is among the most notorious freshwater fishes in the world. As a result, displays featuring this “bloodthirsty” creature are found in most public aquaria, grisly Hollywood movies have been released, and the species has become popular in the aquarium trade. Little of this infamy is based on factual evidence, however.

Following Fink (1993), P. piraya can be distinguished from congeners by the following combination of characters: adipose fin with rays in larger specimens (vs. always without rays in other Pygocentrus species); branched dorsal-fin rays 15-18, usually 16 (vs. 14-18, usually 15); usually 7 neural spines anterior to first pterygiophore (vs. usually 6); vertebrae 36-39, usually 38 (vs. 35-38, usually 36). It can also be identified by colour pattern since it possesses distinctive bright yellow-orange pigmentation on the lower jaw, opercle and lateral body in life.