---
title: "Red-Bellied Piranha (Pygocentrus nattereri) | AnimalTracks.wiki"
description: "Razor-sharp interlocking teeth, a red belly, and a school that doubles as cover from predators."
image: "https://animaltracks.wiki/images/animals/red-bellied-piranha-1.webp"
published: "2026-10-09"
updated: "2026-10-09"
---
# Red-Bellied Piranha (*Pygocentrus nattereri*)
> **Status**: Checked against 7 sources, listed under Sources below.
> **Tagline**: Razor-sharp interlocking teeth, a red belly, and a school that doubles as cover from predators.
> **Soundtrack Vibe**: Math Rock & Instrumental Virtuoso // Battles, "Tonto"
> **Soundtrack Links**: [Spotify](https://open.spotify.com/track/1LyVKKl0Xe1QUpl78z9Bmj)
> **Vibe Match**: A piranha's triangular teeth interlock with a matching set above, a design that gives its bite shearing ability. Battles build "Tonto" from guitar and drum parts that slot into each other like gears.
## Biological Superpowers & Stats
- **Taxonomy**: *Pygocentrus nattereri*
- **Danger Level**: Medium
- **Conservation Status**: Least Concern ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2024-2.rlts.t186604a1815617.en))
- **Superpower**: Triangular, razor-sharp interlocking teeth that bite down with great force and shearing ability
- **Habitat**: Amazon and Paraná-Paraguay river basins, plus rivers of northeast Brazil and the Guianas
- **Diet**: Fins nipped from larger fish, bits of flesh, small fish, insects, aquatic invertebrates and occasional fruit
- **Tags**: fish, freshwater, river, amazon, omnivore, scavenger, social
## Natural History & Behavior
## A Fearsome Reputation
One research team opens a paper by saying red-bellied piranha shoals "have a fearsome reputation." The fish can grow to a little over a foot long (30.5 centimeters) and weigh up to 4 pounds (1.81 kilograms).
It is native to South America east of the Andes: the Amazon and Paraná-Paraguay basins, plus rivers of northeast Brazil and the Guianas. The Smithsonian's National Zoo gives a lifespan of 10 years or more. A study in the Negro River, in Brazil's Pantanal, estimated a life expectancy of 6.9 years for the piranhas there.
## Teeth Like Shears
Under its high forehead sit powerful muscles attached to a short, stout lower jaw. The teeth are triangular and razor sharp, and they interlock with a matching set above. The zoo says this design allows a piranha to bite down with incredible force and shearing ability, which means a slicing cut, like scissors. The teeth are not usually visible: thick, fleshy lips cover them.
## Fins, Flesh and Figs
In the wild, a good portion of the diet is fins nipped from the tails of larger fish. The menu can also include bits of flesh, whole small fish, insects, aquatic invertebrates (animals without backbones) and, occasionally, figs and other ripe fruit. Animal Diversity Web says it can be seen lurking or ambushing prey in the daytime, and lists chasing and scavenging as two other ways it gets food. The zoo calls these fish important scavengers.
Smaller piranhas search for food during the day. Larger fish tend to be more active at dawn and dusk.
## Safety in Numbers
Red-bellied piranhas tend to travel in schools of 20 or more. The Amazon's flooded forests hold a variety and abundance of piranha predators. One team suggested predator defence may be an important reason for shoaling.
Experiments with wild-caught piranhas supported the idea that fish in small shoals perceive more risk, measured by how fast their gill covers beat. After a model cormorant (a fish-eating bird) simulated an attack, piranhas in shoals of eight settled back to resting rates faster than those in shoals of two. The researchers concluded that shoaling has a cover-seeking function in this species.
> **Red-bellied piranhas make sounds** In one study, researchers tied three sounds to three behaviours: a many-pulse sound during frontal display, a single pulse during circling and fighting, and a chasing sound linked to the jaw mechanism.
## Frequently Asked Questions
### Is the red-bellied piranha the most dangerous piranha?
Animal Diversity Web, a University of Michigan database, called it in a 2002 account one of the more dangerous and aggressive species of piranha, and listed injuring humans among its negative effects. The same account said it was one of the most commonly used piranhas in the aquarium trade. *(Source: [Animal Diversity Web, University of Michigan]())*
### Do red-bellied piranhas change colour when they mature?
In a two-year study in Brazil's Mamirauá Reserve that included over 3,000 fish, both males and females reached sexual maturity at around 160 mm. At that point the sexually active fish became dark and lost most of their red colour. The researchers also found two reproductive seasons a year, rather than one, tied to the flooding of the river. *(Source: [Queiroz, Sobanski & Magurran 2010]())*
### Have red-bellied piranhas turned up outside South America?
Yes. A 2002 Animal Diversity Web account says the species has been introduced to fresh waters in the United States many times, with reports from Florida, Hawaii, Massachusetts, Michigan, Minnesota, Ohio, Oklahoma, Pennsylvania, Texas and Virginia. The fish were probably released from aquariums, and the account says that when one turns up in a lake, many state agencies use the chemical rotenone to kill the fish. *(Source: [Animal Diversity Web, University of Michigan]())*
## Sources
1. [Brejão (2024). Pygocentrus nattereri. The IUCN Red List of Threatened Species 2024: e.T186604A1815617.]()
2. [Red-bellied piranha. Smithsonian's National Zoo and Conservation Biology Institute.]()
3. [Pygocentrus nattereri (redbelly piranha). Animal Diversity Web, University of Michigan.]()
4. [Queiroz & Magurran (2005). Safety in numbers? Shoaling behaviour of the Amazonian red-bellied piranha. Biology Letters.]()
5. [Millot, Vandewalle & Parmentier (2011). Sound production in red-bellied piranhas (Pygocentrus nattereri, Kner): an acoustical, behavioural and morphofunctional study. Journal of Experimental Biology.]()
6. [Queiroz, Sobanski & Magurran (2010). Reproductive strategies of Red-bellied Piranha (Pygocentrus nattereri Kner, 1858) in the white waters of the Mamirauá flooded forest, central Brazilian Amazon. Environmental Biology of Fishes.]()
7. [Vicentin, Costa & Súarez (2012). Population ecology of Red-bellied Piranha Pygocentrus nattereri Kner, 1858 (Characidae: Serrasalminae) in the Negro River, Pantanal, Brazil. Environmental Biology of Fishes.]()
*Published October 9, 2026. Last updated October 9, 2026.*
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