Red-bellied piranha

Pygocentrus nattereri

FAMILY

Characidae

TAXONOMY

Pygocentrus nattereri Kner, 1858, Brazil.

OTHER COMMON NAMES

English: Red piranha, redbelly piranha; German: Diamantpiranha, Schulterfleck-Piranha; Natterers Sägesalmler; Spanish: Caribe boca de locha, palometa, paña; Portuguese: Piranha caju; piranha-quexicuda.

PHYSICAL CHARACTERISTICS

Average length of adult 6–8 in (15.2–20.3 cm), but can grow up to 12 in (30.5 cm). Male and female red piranhas are alike externally, with body height about one-half body length. The stocky bodies have reddish bellies, though overall coloration varies depending on location and age. Sides often pale brown to slightly olive; back bluish gray to brownish; throat belly areas bright red. Forked caudal fin usually gray. Pectoral, pelvic, and anal fins typically bright red. Powerful jaws with triangular, interlocking sharp teeth.

DISTRIBUTION

Widely distributed in South America and in basins of the Amazon, Paraguay-Paraña, and Essequibo Rivers, as well as coastal rivers of northeast Brazil.

HABITAT

Creeks and interconnected ponds; prefers areas with dense vegetation.

BEHAVIOR

Diel activity varies by age; adults forage mainly at dusk and dawn, medium-sized individuals are most active at dawn, late afternoon, and night. Smaller fishes feed during the day. Exhibits a "lurking, then dashing" sequence of behaviors during the day. Hierarchical structure often exists in small schools.

FEEDING ECOLOGY AND DIET

Feeds communally, with groups of 20–30 individuals waiting in vegetation to ambush prey. Prey are attacked in a feeding frenzy, further induced by the presence of blood in the water. Highly predaceous carnivores, but also scavenge for food and consume insects, snails, worms, plants, and fins of other fishes. Can feed continuously and maintain a voracious bite by replacing teeth on alternate sides of the jaw. Preyed upon by other fishes (including large pimelodid catfishes), crocodilians, fisheating birds, and large mammals (including jaguars).

REPRODUCTIVE BIOLOGY

Spawns through external fertilization. After elaborate courtship display involving swimming in circles, the female deposits layers of eggs on plants in the water, and the male fertilizes them. The male guards and fans the egg masses until they hatch in 9 to 10 days. Annual reproductive success varies, but is dependent upon the degree to which the savanna is flooded.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

This species is kept as an aquarium fish. This activity is illegal in some states of the United States to prevent irresponsible hobbyists from releasing the species into the wild, where it may multiply and prey upon indigenous fish species. These fish can also inflict serious bites, although they are not as aggressive as once believed, and they are unlikely to attack humans unless the human is bleeding or in water near congregations of other prey species. The species is commonly caught and eaten by river dwellers throughout its extensive range. Large numbers are also caught for use as trot-line bait for large catfishes.