# Red-bellied Piranha (*Pygocentrus nattereri*)

> The red-bellied piranha (Pygocentrus nattereri) is a freshwater fish of the Amazon basin, famous for its interlocking triangular teeth and reddish belly. Adults grow to about 20 to 35 cm long and weigh up to roughly 1.5 kg, swimming in large shoals through rivers, streams and flooded forests. Despite their fearsome reputation, they are mainly scavengers and opportunistic feeders. They are common and listed as Least Concern.

- **Category:** Fish
- **Conservation status (IUCN):** Least Concern
- **Range:** Rivers, streams, and floodplains of the Amazon basin and other river systems of tropical South America.
- **Canonical page:** https://globalanimalguide.org/animals/piranha/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Actinopterygii
- **Order:** Characiformes
- **Family:** Serrasalmidae
- **Genus:** Pygocentrus

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Pygocentrus nattereri |
| Diet | Omnivore (mostly carnivorous) |
| Habitat | Amazon rivers, streams, and floodplains |
| Lifespan | About 10 years |
| Length | 20–35 cm (8–14 in) |
| Top speed | Fast in short bursts |
| Conservation status | Least Concern (IUCN) |

## Teeth and feeding

Red-bellied piranhas have a single row of sharp, triangular teeth in each jaw that lock together like a pair of scissors, letting them shear off pieces of flesh with a single snap. They are omnivores that are mostly carnivorous, eating fish, insects, crustaceans, worms and carrion, along with seeds and plant matter when animal food is scarce. Feeding frenzies do occur, but usually only when food is limited or a shoal encounters an easy meal such as a dead or injured animal. Much of the time they nip fins and scales from other fish rather than consuming whole prey.

## Life in a shoal

Red-bellied piranhas gather in shoals that can number from a handful to several hundred fish. Rather than being packs of coordinated hunters, these groups are thought to offer protection from predators such as caimans, larger fish, river dolphins and birds. Fish on the edge of a shoal stay more alert, and the group provides safety in numbers for an animal that is itself widely eaten. Shoaling also helps them locate food and defend feeding sites.

## Habitat and range

This species lives throughout the Amazon river basin and other river systems of tropical South America, favouring slow-moving rivers, streams, oxbow lakes and seasonally flooded forest. During the wet season they spread out across the inundated floodplain, where food is abundant and breeding takes place. As waters recede in the dry season, they become concentrated in shrinking pools, which is when reports of aggressive feeding are most common. They tolerate warm, oxygen-poor water better than many fish.

## Reproduction

Breeding peaks in the wet season, when females scatter thousands of eggs among submerged vegetation in the flooded forest. Unusually for fish, red-bellied piranhas guard their nests, with parents defending the eggs and clearing a patch of plants to lay them on. The eggs hatch within a few days, and the fry shelter among plant cover until they are large enough to join a shoal. This parental care improves the survival of the young in predator-rich waters.

## Reputation versus reality

Piranhas have a reputation as bloodthirsty killers that can strip an animal to the bone in minutes, an image cemented by adventure stories and film. In reality they are timid fish that spend much of their time avoiding predators, and healthy large animals crossing a river are usually ignored. Serious bites to people are rare and typically happen when fish are crowded into low water or handled by anglers. They do have genuinely powerful jaws, and a careless hand near a caught piranha can be badly nipped.

## Frequently asked questions

### Do piranhas really attack humans?

Attacks on people are rare and rarely serious. Most bites happen when piranhas are trapped in shrinking dry-season pools or when anglers handle them. Healthy swimmers are generally ignored, though a caught piranha can deliver a painful nip.

### What do red-bellied piranhas eat?

They are omnivores that feed mostly on animal matter, including fish, insects, crustaceans, worms and carrion. They also eat seeds and plants when other food is scarce. Much of their diet comes from scavenging and nipping the fins of other fish.

### How big do red-bellied piranhas get?

Adults typically reach about 20 to 35 cm in length and weigh up to around 1.5 kg. They are stocky, deep-bodied fish, but they are far smaller than their fearsome reputation suggests.

### Why do piranhas swim in groups?

Piranhas form shoals mainly for protection rather than for hunting. Grouping together reduces each fish's chance of being taken by predators such as caimans, birds and larger fish. The shoal also helps them find food and defend feeding areas.

### Are piranhas endangered?

No. The red-bellied piranha is common and widespread across the Amazon basin and is listed as Least Concern by the IUCN. It is not considered threatened and remains an abundant fish across its range.

### How long do piranhas live?

Red-bellied piranhas live for about 10 years. They can live longer in aquariums with good care, where they are sometimes kept, though their strong jaws demand caution from keepers.

## Sources

- [IUCN Red List — Pygocentrus nattereri.](https://www.iucnredlist.org/search?query=Pygocentrus%20nattereri&searchType=species)
- [Animal Diversity Web — Pygocentrus nattereri. University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Pygocentrus_nattereri/)
- [Wikipedia — Red-bellied Piranha.](https://en.wikipedia.org/wiki/Red-bellied_piranha)

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Source: Global Animal Guide (https://globalanimalguide.org/animals/piranha/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.