Marine Biology

Fish Profile Red Bellied Piranha

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Red-bellied piranha (Pygocentrus nattereri) has a characteristic red-belly. The other colors on its body vary though it is generally grey in appearance. This fish has a reputation for aggression with its sharp teeth. It is around thirteen inches in length. It weighs nearly eight pounds. The fish also has silvery scales on its sides. The males have more red than the females.


This piranha makes its home in South America where it likes fast moving white water. It likes the flooded forests of the Amazon as well. It lives in groups but does not hunt with others.

This piranha does not like to eat the flesh of humans. Its tastes include those of an omnivore and herbivore than a carnivore. It likes insects, other fish, crabs and mollusks. They have a special sense inside their bodies that allows them to locate their food by movement or smell. It even lives on fruits, algae and plants. Despite its reputation, it rarely attacks in groups.


When the red-belly does seem to attack in a group, as in a feeding frenzy, it is because the prey is large or food was not readily available to it. The only time the piranha, attacks in groups, is when it feels threatened or it hasn't eaten in a long time.


The male builds the rounded nest for the female during the wet season usually April or May. The female can lay 5,000 eggs on foliage that has recently fallen from the trees. During the breeding season, she may have a more yellowish belly. The male protects the eggs. When they hatch, both parents protect and care for the young.

Erroneous Reputation

Movie makers have erroneously portrayed this fish as a killer. In reality, it mainly consumes dead or dying fish and aquatics. They keep the streams and rivers where they live clean.


Collectors are the biggest threats to these fish. People want to keep them in their aquariums. So, the piranhas disappear from their native homes. Piranhas in captivity react much differently than piranhas in the wild. Some wildlife agencies do not let people in all countries have this fish as a pet.

 Captive Red-belly Piranhas

Red-bellies do well in large aquariums of over 300 gallons. To keep them content and less aggressive, keep four piranhas together. Feed them fresh meat not other fish. Other fish may carry harmful bacteria. These fish like to hide, especially in captivity, so don't expect to see them often.  Frequent water changes are necessary and a pH of 5.5 to 7 is required for these fish to live comfortably in an aquarium. 

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