Castelnau´s Piranha

About

Castelnau's Piranha (Serrasalmus gibbus) is one of those species that demands respect from the moment you research it. Native to the Tocantins River basin in Brazil, this mid-sized piranha carries the classic serrasalmid profile. A deep, laterally compressed body, a blunt snout, and the kind of jaw you don't want near your fingers during tank maintenance. The common names gold piranha and silver-scaled piranha hint at the metallic sheen that can appear across its flanks, though coloration varies with age and condition. In the wild, the Tocantins is a fast-moving river system, and fish from these habitats tend to be alert and reactive. In captivity, that translates to a fish that is perpetually on edge and absolutely cannot be housed with other fish. Not other piranhas, not dither fish, not anything. This is a strict solitary species, and any attempt at tankmates typically ends badly. Despite that uncompromising temperament, the care level is listed as beginner-accessible, which largely comes down to diet and water conditions being straightforward to manage. That said, "beginner" here means someone who understands aggressive, solitary predators. Not someone setting up their first community tank.