There are more than 80 species of piranha, most of which are herbivores.
The female lays her eggs on beds of aquatic leaves that the male builds by cutting up plants with his sharp teeth. The clutch is then guarded and ventilated by both parents. A female can produce up to 5,000 eggs that take four days to hatch.
The red-bellied piranha is a carnivore, feeding mostly on fish. However, it can also attack larger prey as a group, when an animal is sick or injured. This helps to rid the environment of animals that would become a source of pollution if left to decompose.