Animal
Red-bellied piranha
The red-bellied piranha is a fish from South America. It has a red tummy, a silver back and a strong mouth.
The red-bellied piranha is a silver fish with a red belly that lives in rivers, creeks and floodplain ponds of South America. It has a famous reputation, but experts say the danger to people is greatly exaggerated: piranhas mostly eat fish, insects, snails and plants.
Pygocentrus nattereri is a schooling serrasalmid of the Amazon, Paraná-Paraguay and coastal basins east of the Andes. Its sharp, serrated teeth and schooling habits are famous, yet USGS notes that many experts consider its danger to humans greatly exaggerated. The IUCN lists it as Least Concern with a stable population.
Photo: Gregory Moine from Niantic, USA, CC BY 2.0, via Wikimedia Commons
Meet the red-bellied piranha
The red-bellied piranha is a fish with a red tummy.
Its back and sides are silver and gray. It lives in big rivers in South America. Piranhas like to swim together in groups.
The red-bellied piranha is a deep-bodied fish with a silver-gray back and a reddish-orange belly. It lives in rivers, creeks and flooded ponds in South America and swims in groups called schools.
Piranhas are famous for their sharp teeth and have a reputation as man-eaters. Scientists see them differently. Piranhas mostly eat fish, insects, snails and plants, and many experts think stories about piranhas attacking people are greatly exaggerated.
Pygocentrus nattereri belongs to the Serrasalmidae, the family of piranhas and pacus. Adults are silver-gray above and reddish-orange below, with dark dorsal and anal fins; Animal Diversity Web notes that color, spotting and body size vary with age and locality.
It is one of the more aggressive piranhas and the most common in the aquarium trade, yet USGS reports that many experts consider its danger to humans greatly exaggerated. Field studies describe a varied diet and complex group behavior, a richer picture than its reputation.
Quick facts
- Group
- Fish
- Length
- 15 to 24 cm
- Weight
- up to 3.9 kg
Where it lives
Red-bellied piranhas live in South America.
They swim in big rivers like the Amazon. When the rains come, the rivers rise. Creeks and ponds join up, and the piranhas swim there too.
Red-bellied piranhas live in South America, east of the Andes Mountains. Their home includes the giant Amazon River basin, the Paraná and Paraguay rivers farther south, and coastal rivers in Brazil and the Guianas.
They are found in a dozen countries, from Venezuela and Colombia south to Argentina and Uruguay. They like muddy, whitewater rivers and the creeks and ponds that link up during floods, and they are rarely found in dark blackwater rivers.
The IUCN global assessment lists native populations in Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Uruguay and Venezuela, with an introduced population in Hawaii. USGS describes the range as lowland central and southern South America east of the Andes, including the Amazon and Paraná basins and coastal drainages of the Guianas and Brazil.
The species typically lives in sediment-rich whitewater and is not usually found in blackwater (ADW). FishBase notes it is common in creeks and interconnected ponds in Mato Grosso, Brazil, where it shapes how other fish feed and where they live.
Continent
Its habitats
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Lowland rivers, creeks and floodplain ponds east of the Andes: the Amazon, Paraná-Paraguay and coastal river basins of Brazil and the Guianas. It lives only in rivers and wetlands within each country shown. French Guiana is also in its range but is not shown separately on this map.
Places: Argentina, Bolivia, Brazil, Colombia, Ecuador, Guyana, Paraguay, Peru and 3 more places.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Brazil, Peru, Bolivia, Argentina, Colombia, Paraguay, Ecuador, Guyana and 11 more places.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
What it eats
Piranhas eat fish, insects, snails and plants.
They also eat dead fish they find in the river. Young piranhas look for food in the daytime.
Red-bellied piranhas eat a surprising mix of foods: whole fish, bits of fins and scales, insects, snails, shrimp-like animals, worms and even plants. They also scavenge, which means they eat animals that are already dead.
Young piranhas, about 8 to 11 centimeters long, hunt mostly in the daytime. Bigger ones feed mainly at dawn, in the late afternoon and into the evening.
USGS describes P. nattereri as a schooling predator that takes live fish whole or removes pieces of fin, scale or muscle, and also eats crustaceans, insects, molluscs and plant material, as well as scavenging on carcasses. Animal Diversity Web suggests plant intake may be a way to feed while scanning for prey.
Foraging changes with size. FishBase reports that small fish of 8 to 11 centimeters are mostly active by day, while fish of 15 to 24 centimeters forage at dawn, in the late afternoon and at night until about 22:00. Groups of 20 to 30 may wait among vegetation and then dash out.
Did you know?
Piranha parents guard their eggs.
Red-bellied piranhas guard their sticky eggs until they hatch, about 9 to 10 days later.
Eggs adhere to submerged roots or plants, are guarded and are not eaten by the parents (FishBase).
Teeth, color and senses
A piranha has a row of sharp, pointy teeth.
Its belly is red and its back fin is dark. Piranhas hear very well underwater.
A piranha's jaws hold a single row of sharp teeth with tiny saw-like edges. New teeth replace old ones on one side of the jaw at a time, so the fish can keep eating.
This piranha's colors help name it: a reddish-orange belly, gray-silver sides, black back and bottom fins and reddish-orange side fins. Piranhas also have excellent hearing.
Piranhas have a single row of sharp, incisor-like, serrated teeth, which USGS uses to tell them from pacus, whose teeth are molar-like and set in two rows. FishBase notes that teeth are replaced on alternating sides of the jaw, which allows continuous feeding, and that its powerful dentition can inflict serious bites.
The body is deep and compressed, with 16 to 18 dorsal-fin rays and 27 to 30 anal-fin rays. ADW describes the reddish-orange underside, silver-gray back and black dorsal and anal fins. FishBase credits the species with a highly evolved auditory capacity, and males and females look alike from outside.
Nests and eggs
Piranhas lay their eggs in the rainy season.
The parents make a round nest on the river bottom. The eggs stick to plants. Baby piranhas hatch after about ten days.
Red-bellied piranhas breed during the rainy season, when rivers rise and flood. A male and female swim in circles as part of their courtship. Then they make a bowl-shaped nest about 15 centimeters wide in the soft bottom.
The eggs are laid in clusters stuck to plants or to tree roots hanging in the water, and the parents guard them. The eggs hatch in 9 to 10 days.
Spawning appears to coincide with the wet season; USGS gives roughly October to February. Animal Diversity Web describes a circling courtship and bowl-shaped nests about 4 to 5 centimeters deep and 15 centimeters across, with eggs in clusters attached to vegetation. FishBase reports large adhesive eggs laid on submerged tree roots, guarded but not eaten by the parents, hatching in 9 to 10 days.
Reproductive success varies strongly from year to year with how widely the savanna floods. FishBase's model, using a fecundity of about 4,000 to 5,000 eggs, estimates a minimum population doubling time of 1.4 to 4.4 years.
Life in a school
Piranhas swim together in a group called a school.
A group may wait quietly among plants. Then they all swim off fast.
Red-bellied piranhas live in schools. A school of 20 to 30 fish may wait quietly among water plants, then dash out after prey. Inside a small school, some fish rank above others.
Piranhas also chase prey and scavenge. Their reputation as a fearsome pack that attacks people is mostly a story: many experts say the danger to humans is greatly exaggerated. Fish keepers still handle piranhas carefully, because their teeth are sharp.
P. nattereri is a schooling species. FishBase describes hierarchies within small schools and a daytime pattern of lurking followed by a sudden dash. Animal Diversity Web adds that groups of about 20 to 30 fish gather in vegetation to ambush prey, and that chasing and scavenging are also used.
Its reputation as a man-eater is another matter: USGS notes that many experts consider the species' danger to humans greatly exaggerated. People who handle live piranhas, such as aquarium keepers and fishers, still treat them with care, because a bite can be serious.
Rivers and people
Red-bellied piranhas are not in danger.
There are lots of them. People who live by the rivers catch them for food. Healthy rivers keep piranhas healthy too.
The IUCN lists the red-bellied piranha as Least Concern, and its numbers are stable. People who live along South American rivers catch piranhas for food and sport, and many are sold as aquarium pets.
Its rivers face problems. Dams change how water flows, and pollution from industry can harm the water. Pet piranhas must never be let go: some have been found in lakes in the United States, and many southern US states ban bringing them in.
The IUCN global assessment (assessed December 2020, published 2024) lists P. nattereri as Least Concern with a stable population. It names dams and water management, and industrial effluents, as threats, and records use as pets, food and in handicrafts. FishBase classes it as a minor commercial fishery and a gamefish.
Probable aquarium releases have produced records in many US states. USGS lists every one as a failed introduction: in northern states, fish are usually caught in summer or found dead in cooler months, and the species' chronic thermal minimum is estimated at 10 °C. The IUCN, however, lists an introduced population in Hawaii. Import is prohibited in many southern states, including Florida and Texas.
Did you know?
Piranhas grow new teeth when old ones wear out.
Piranhas replace their teeth one side of the jaw at a time, so they never have to stop eating.
Tooth replacement on alternating sides of the jaw lets piranhas feed continuously (FishBase).
Amazing facts
-
Piranhas grow new teeth when old ones wear out.
Piranhas replace their teeth one side of the jaw at a time, so they never have to stop eating.
Tooth replacement on alternating sides of the jaw lets piranhas feed continuously (FishBase).
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Piranhas eat plants too, not only fish.
Red-bellied piranhas eat plants as well as fish, insects and snails.
Plant material is a regular part of the diet; ADW suggests it may be eaten while the fish scans for prey.
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Young piranhas look for food by day. Big ones look at dawn and dusk.
Small piranhas feed mostly in the daytime, while bigger ones feed at dawn, late afternoon and into the night.
FishBase reports that fish of 8 to 11 cm forage by day and fish of 15 to 24 cm at dawn, late afternoon and night.
-
Piranha parents guard their eggs.
Red-bellied piranhas guard their sticky eggs until they hatch, about 9 to 10 days later.
Eggs adhere to submerged roots or plants, are guarded and are not eaten by the parents (FishBase).
Words to know
- school
- a group of fish that swim together
- scavenge
- to eat animals that are already dead
- serrated
- having a sharp, saw-like edge
- whitewater river
- a river that is muddy and pale with lots of fine soil
- basin
- all the land drained by a big river and the streams that flow into it
- reputation
- what many people believe about someone or something
Discovery challenge
-
Where do red-bellied piranhas live?
On which continent do red-bellied piranhas live in the wild?
On which continent is the red-bellied piranha native?
- South America
- Europe
- Antarctica
Show the answer
South America
Red-bellied piranhas live in rivers in South America.
They live in rivers of South America east of the Andes, including the Amazon.
Native to twelve South American countries across the Amazon, Paraná-Paraguay and coastal basins.
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What do piranhas eat?
Which list shows foods red-bellied piranhas really eat?
Which best describes the red-bellied piranha's diet?
- Fish, insects, snails and plants
- Only people
- Only leaves
Show the answer
Fish, insects, snails and plants
Piranhas eat fish, bugs, snails and plants.
Their diet is broad: fish, insects, snails, shrimp-like animals, plants and dead animals.
A broad diet of fish, crustaceans, insects, molluscs and plants, plus scavenging (USGS).
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How do piranhas like to swim?
How do red-bellied piranhas usually live?
What social structure do red-bellied piranhas show?
- Alone all the time
- In groups called schools
- Out of the water
Show the answer
In groups called schools
Piranhas swim together in groups.
They live in schools, and groups of 20 to 30 may wait together among plants.
They school, with hierarchies within small schools (FishBase).
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What happens to a piranha's teeth when they wear out?
What happens when a piranha's teeth wear out?
How do piranhas keep feeding while replacing teeth?
- New teeth grow in
- It stops eating forever
- It grows a beak
Show the answer
New teeth grow in
New teeth grow in, so the piranha can keep eating.
New teeth replace worn ones, one side of the jaw at a time.
Teeth are replaced on alternating sides of the jaw, which allows continuous feeding.
Places where you might see it
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Watch
Country
Brazil
Brazil covers about half of South America and is the fifth-largest country in the world. It holds most of the Amazon River basin and much of the world's largest rainforest, and about 214 million people lived there in 2026, most of them near the Atlantic coast.
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Watch
Country
Peru
Peru is a country on the Pacific coast of South America. It has a dry desert coast, the high Andes mountains and the Amazon rainforest, and about 34 million people lived there in 2025, many of them in the capital, Lima.
Explore next
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Watch
Country
Brazil
Brazil covers about half of South America and is the fifth-largest country in the world. It holds most of the Amazon River basin and much of the world's largest rainforest, and about 214 million people lived there in 2026, most of them near the Atlantic coast.
-
Watch
Country
Peru
Peru is a country on the Pacific coast of South America. It has a dry desert coast, the high Andes mountains and the Amazon rainforest, and about 34 million people lived there in 2025, many of them in the capital, Lima.
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Amazon river dolphin
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Neon tetra
The neon tetra is a tiny fish, about as long as a quarter is wide, with a glowing blue stripe and a bright red patch. In the wild it lives in clear and dark-water forest streams of the western Amazon. It is also one of the most popular aquarium fish in the world.
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Giant otter
The giant otter is the longest otter in the world, up to about 1.8 meters from nose to tail. It lives in the rivers and lakes of South America in noisy family groups that hunt fish together by day. It is endangered, and people are working to protect it.
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Alligator gar
The alligator gar is one of the largest freshwater fish in North America. It has a broad snout lined with teeth, armor-like scales, and a swim bladder that works like a lung, so it can gulp air in warm, still water. It lives in the big rivers, swamps and bayous of the southern United States, Mexico and Central America.
For parents & teachers
What children will learn
- Locate the red-bellied piranha's range in South American river basins.
- Describe its varied diet and how feeding times change as it grows.
- Explain how scientists' findings differ from the piranha's popular reputation.
- Describe how floods and the rainy season shape its breeding.
Recommended ages: 3 to 17 · About 12 minutes
Talk about it
- Why do you think piranhas got such a scary reputation?
- How might living in a school help a fish stay safe?
- Why could releasing a pet fish into a lake be a problem?
Try at home or in class
- Draw a piranha and label its belly, back fin, bottom fin, tail and jaw using the colors described in the body section.
- Make a two-column chart of 'stories people tell' and 'what scientists found' about piranhas.
Key vocabulary: school, scavenge, serrated, whitewater river, basin, reputation
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Pygocentrus nattereri (Piranha-vermelha), global assessment , IUCN Red List of Threatened Species
- Red piranha (Pygocentrus nattereri) species profile , U.S. Geological Survey, Nonindigenous Aquatic Species
- Pygocentrus nattereri, Red piranha , FishBase
- Pygocentrus nattereri (red-bellied piranha) , Animal Diversity Web, University of Michigan Museum of Zoology
- Red-bellied pacu (Piaractus brachypomus) species profile (piranha and pacu teeth) , U.S. Geological Survey, Nonindigenous Aquatic Species
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.