The „real“ piranha, Pygocentrus piraya, is restricted to the river system of the Sao Francisco in southern Brazil. It is a up to 30 cm long species, which is characterized by its deep red breast and the mighty jaws when it is fully grown.However, even juveniles display a very attractive coloration.
Most piranha species belong to the genus Serrasalmus. Externally Pygocentrus and Serrasalmus are very similar, but the behaviour of the members of the two genera is completely different. All Serrasalmus are fin eaters and solitary fish whereas all three Pygocentrus species (P. caribe, P. nattereri and P. piraya) are schooling fish.
This means that P. piraya should be kept in real big aquaria, as it becomes a large fish and must be kept in groups. When they reach maturity, pairs build up small territories (places around large plants are most wanted). They dig out spawning pits by hitting away the gravel with the caudal fin and defend this against other fish. Only the male defends eggs (many thousands) and fry. The brood care ends when the young become free swimming.
Usually no piranha will attack a human being. Nevertheless you should keep respect as the fish have razorsharp teeth and can give really heavy bites. There is only real danger when the aquarium is too small for the fish and they cannot get out of the way or during feeding times, as by chance the piranha can take the keeper’s finger for food by mistake.
All in all P. piraya is a gorgeous fish for show tanks where it can also show its faszinating and highly developed behaviour.
Text & Photo: Frank Schäfer