Scientific name: Pygocentrus nattereri
Country: Argentina, Bolivia, Brazil, Colombia, Ecuador, Guyana, Paraguay, Peru, Uruguay, Venezuela
Continent: South America
Food & feeding: Fish, insects, crustaceans, worms, plant material and carrion.
Conservation status: Not threatened
Relatives: Black piranha
Description: Adult fish grow up to 33 cm long weighing a maximum of 3.5 kg. Juveniles have silver bodies with dark blotches whereas the adults develop a characteristic red belly. Male piranhas have a more intense red belly then the females, especially during breeding. Piranhas have a single row of sharp teeth in their upper and lower jaws. These teeth are tricuspid (three points) with a large, triangular blade-like middle cusp. Extremely sharp, the teeth are tightly packed and interlock, making them excellent for puncturing and shearing flesh.
Lifestyle: Piranhas live in shoals, in both lotic (rivers & streams) and lentic (lakes) environments. Shoaling creates a feeling of ‘safety in numbers’ for these fish. They do not show co-ordinated hunting behaviour but will go into a feeding frenzy if they are starved and a large prey item becomes available.
Family & friends: Piranhas are schooling animals, forming a loosely associated group with other fishes. Sexually mature adults maintain a spot in the middle of the shoal.
Keeping in touch: Piranhas have good hearing and can produce a drumming sound by causing vibrations with their muscles that resonate through the gas-filled swim bladder. The sound of splashing (potentially form a struggling animal), or the presence of blood in the water triggers them to start looking for food. Piranhas have a special line of sensors down the sides of their bodies, called the lateral line system. This picks up changes in water pressure, currents and the movements of other animals in the water.
Growing up: Red-bellied piranha usually spawn during the rainy season, around April and May. The male will build a dug-out nest in rocks and the female will then lay 600 eggs or so, which the male then fertilizes. Males become extremely territorial during spawning, and will prevent other fish from approaching the nest. After the eggs hatch, both parents guard the brood. The young piranha spend their time feeding and hiding amongst the weeds, joining a shoal once they attain a length of 5 cm. The young piranha are situated on the outside of the shoal, where they are able to feed easily. As they reach sexual maturity they move into the centre of the shoal, where it is safest from predators.
Conservation news: Piranhas are sometimes dried out and used as souvenirs and are kept as pets.