Piranha

The piranha (also known as the caribe or piraña) is a ferocious, schooling, fresh-water fish. It is native to warm lowland streams and lakes in South America, east of the Andes Mountains. Piranhas have been introduced to other places, including Northern Brazil, Hawaii, and parts of Central and North America. There are many species of piranha; they belong to the genera "Pygocentrus" and "Serrasalmus". They reproduce by laying eggs.
Diet.
Piranhas are opportunistic carnivores (flesh-eaters). They eat aquatic and land animals that are in the water. Some of the prey includes fish, mollusks, crustaceans, insects, birds, lizards, amphibians, rodents, and carrion (dead meat that they find). These fish are diurnal (most active during the day).
Predators.
Many animals prey upon piranhas (especially young piranhas), including other piranhas, caimans, water snakes, turtles, birds, otters, and people.