Any of several species of deep-bodied, carnivorous fishes in the genus Serrasalmus (family Characidae), abundant in rivers of eastern and central South America and noted for voracity. The red-bellied piranha (S. nattereri) grows to 2 ft (60 cm) long, but most species are smaller. Some species are silvery with an orange belly and throat; others are almost completely black. All have sharp, saw-edged teeth that close in a scissorlike bite. Traveling in groups, they usually prey on other fishes, but red-bellied piranhas occasionally converge on larger animals. Though generally scavengers, they are attracted to the scent of blood and can quickly reduce even a large animal to a skeleton.

Learn more about piranha with a free trial on Britannica.com.