How many of the piranas are dangerous?

Not all piranha species are dangerous, but the most notorious ones, such as the red-bellied piranha (Pygocentrus nattereri), are known for their aggressive behavior and powerful bite. While they can pose a threat to humans, attacks are relatively rare, and they typically do not hunt large animals. Most piranhas are scavengers or primarily feed on smaller fish. Overall, the danger they present largely depends on the species and the circumstances.