Red-bellied piranha

The red-bellied piranha, also known as the red piranha (Pygocentrus nattereri), is a species of piranha native to South America, found in the Amazon, Paraguay, Paraná and Essequibo basins, as well as coastal rivers of northeastern Brazil. This fish is locally abundant in its freshwater habitat. They are omnivorous foragers and feed on insects, worms, crustaceans and fish. They are not a migratory species, but do travel to seek out conditions conducive to breeding and spawning during periods of increased rainfall. Red-bellied piranhas often travel in shoals as a predatory defense, but rarely exhibit group hunting behavior. Acoustic communication is common, and is sometimes exhibited along with aggressive behaviors. Through media influence, the red-bellied piranha has developed a reputation as a ferocious predator, though this is not actually the case. They are a popular aquarium fish. The red-bellied piranha belongs to the family Serrasalmidae, which is a group of medium to large-sized characids and includes other closely related omnivores such as pacus. They are characterized by deep, lateral compressed bodies and long dorsal fins. Within the family, red-bellied piranhas are classified in the genus Pygocentrus, which is distinguished by the unusual dentition and differing head width dimensions. The red-bellied piranha is considered to be highly carnivorous, while most other fish that are not piranhas in the family are primarily herbivorous. However, the red-bellied piranha is actually omnivorous. The red-bellied piranha is distributed widely throughout the South American continent and is found in the Neotropical rivers of Argentina, Brazil, Bolivia, Colombia, Ecuador, Guyana, Paraguay, Peru, Uruguay, and Venezuela. They live in the warm freshwater drainages of several major rivers including the Amazon, Paraguay, Paraná and Essequibo, as well as numerous smaller systems.They can live in waters that are between 15 and 35 °C (59–95 °F), but are able to survive temperatures as low as 10 °C (50 °F) for a period. They are mainly found in whitewater, but have also been recorded in blackwater and clearwater. The red-bellied piranha live in major rivers, streams, lakes (such as oxbows and artificial lakes formed by dams), floodplains, and flooded forests. The red-bellied piranha has a popular reputation as a ferocious predator, despite being primarily a scavenger. As their name suggests, red-bellied piranhas have a reddish tinge to the belly when fully grown, although juveniles are a silver color with darker spots. The species can reach up to 3.9 kg (8.6 lb) in weight and 50 cm (20 in) in standard length, but rarely surpass 35 cm (14 in). The rest of the body is often grey with silver-flecked scales. Sometimes, blackish spots appear behind the gills and the anal fin is usually black at the base. The pectoral and pelvic fins may vary from red to orange. Females can be distinguished from males by the slightly deeper red color of their bellies. The red-bellied piranha is typically found in white water rivers, such as the Amazon River Basin, and in some streams and lakes. Sometimes, they may inhabit flooded forests such as those found in the Brazilian Amazon. They live in shoals but do not group hunt, although they may occasionally enter into feeding frenzies. In the case of a feeding frenzy, schools of piranha will converge on one large prey individual, and eat it within minutes. These attacks are usually extremely rare and are due to provocation or starvation. Breeding occurs over a two-month period during the rainy season, but that can vary by area. Females will lay around 5,000 eggs on newly submerged vegetation in nests that are built by the males. Pygocentrus nattereri encompasses a larger geographic area than any other piranha species, covering much of the Neotropical region. When red-bellied piranhas are introduced to other parts of the American continent, there are usually negative consequences for the local fish fauna, partially due to its generally aggressive behavior. This aggressive behavior is sometimes marked by the acoustic sounds they produce. The red-bellied piranha is not a migratory species, but does search for conditions conducive to reproduction during seasons of increased rainfall. Red-bellied piranhas are omnivores and primarily foragers. They feed on insects, fish, plants, and organic debris. The typical diet of red-bellied piranhas includes insects, worms, crustaceans, and fish. In packs up to hundreds, piranhas have been known to feed on animals as large as egrets or capybara. Despite the piranha’s reputation as a dangerous carnivore, it is actually primarily a scavenger and forager, and will mainly eat plants and insects during the rainy season when food is abundant. They also tend to only feed on weak, injured, dying, or dead animals in the wild. Red-bellied piranhas do not stay in groups in order to pack-hunt for larger animals, but instead group for protection against predators.