red piranha

The bodies of juveniles are silver, covered with more or less large black spots. They are easily confused with other young fish of the Serrasalmidae family.

As adults, the black spots disappear and the belly becomes red on a slightly golden body. It resembles the San Francisco piranha but the latter is larger with a golden body, not red.

The red piranha lives in groups of dozens of individuals, according to a well-established hierarchy. Naturally, it resides at mid-depth and close to the surface where it can catch small prey.

It is sometimes seen hunting near banks and dead trees. It is not a "big" predator but rather an opportunistic and scavenging species. In its environment, it plays the role of a "sanitary" cleaner, preferring to target weak, injured, and sick species.

Adult feeding mainly occurs at dusk and dawn. It consists of insects, worms, and fish, less often lizards or birds. Juveniles feed on invertebrates and smaller fish throughout the day. Both young and adults also feed on corpses (including humans), scales, and mollusks. A small amount of vegetation is included in their diet.

In general, they alternate between rest periods and intensive hunting. When resting, they camouflage themselves in vegetation and remain still. Studies have shown that aggressiveness increases directly with water temperature. Around 35 °C, they adopt a clear aggressive behavior and many individuals bear the scars of these phases (torn fins, bites...). Conversely, they stop hunting other fish below 10 °C, a minimum temperature that generally marks the end of their range

During the breeding season, piranhas stop feeding. They may bite to defend their nests if disturbed.

Their preferred predators are freshwater dolphins, otters, and large carnivores in their habitat. This species, abundant in its native areas, plays a central role in the distribution and feeding of other fish.

Contrary to popular belief, piranhas, although cannibalistic, are attentive parents during the early stages of the breeding process.

The male builds a nest dug in flooded grass, gravel, plant debris, or among tree roots. Reproduction success varies from year to year depending on flood conditions. Generally, red piranhas are particularly prolific. Females lay between 5,000 and 20,000 eggs (the number varies according to sources).

The detailed reproduction process is not well-known, but observations show that it takes place during the wet season, when waters are rising and food is abundant. Groups then move to freshly flooded areas to prepare the nests. Reproduction has been recorded at around 27 °C, 35 centimeters deep. Once the males have finished the nests, females approach and courtship displays occur. Mated pairs then perform synchronized circular movements.

Eggs are laid in the nest, and they are large. Attached in clusters, they adhere to roots and grass stems. They are not attacked by the parents. According to sources, either the parents or only the male protects the nest. Around 27 °C, hatching occurs after about ten days.