About Serrasalmus rhombeus (Linnaeus, 1766)
The redeye piranha, scientifically named Serrasalmus rhombeus (Linnaeus, 1766), is the largest piranha species. It has a distinctly rhombus-shaped body, with solid colouration ranging from grey to nearly black. All individuals of this species, regardless of body colour, have red eyes. Juvenile redeye piranhas typically have more mottled colouration than adults. As they mature, their originally silvery bodies become less mottled and shift to a darker grey or black. How dark individual fish become depends on local water conditions: fish found in Peru are the darkest, and may be almost jet black. The maximum recorded standard length of this species is 41.5 to 61 centimetres (16.3 to 24.0 in), while a more typical adult length is around 32 centimetres (13 in). The maximum recorded weight for the species is 3.0 kilograms (6.6 lb).
Redeye piranhas are native to northern South America, east of the Andes Mountains. They occur naturally in the Amazon and Orinoco drainage systems, the Essequibo River, other rivers of the Guiana Shield, and the coastal rivers of northeastern Brazil. The species was introduced to Florida, but it is now extirpated there.
This species occupies a wide variety of habitats. Adults prefer large, deeper river channels, and usually hunt for prey either in deep stretches or near rapids. Juveniles are most commonly found in slower, stiller stretches of water with thick submerged or marginal vegetation. Paler coloured fish tend to live in turbid white waters, while dark coloured fish are predominant in clear or dark waters. Redeye piranhas are opportunistic omnivorous feeders. They consume plants, fallen fruits, and smaller animals including insects and small fishes. They will also nip and eat scales and fins from other fishes. They are well known scavengers, and feed on animal carcasses in their river habitats. This is not a social species, and normally lives alone. At minimum during breeding, they defend a territory around their nest, which is placed among thick vegetation.
