There is a small fish in the Amazon basin of South America. It is only about 21 cm long, with a flat body and silvery scales mixed with brown spots. It looks lost face-free and unobtrusive, but it is the most ferocious fish in the world-piranha.

Piranha has triangular teeth all over its mouth, sharper than a razor. It not only attacks animals in the water crazily, but also jumps out of the water to attack large waterfowl. Piranhas are particularly sensitive to blood, and a little blood and a little smell of blood will make them come in droves. It can be said that any river with piranhas becomes a terrible river. Because

if animals or people on land unfortunately fall into such a river, in a few minutes, the large animals that were alive and kicking just now will suddenly become a skeleton. They even attack their own kind. If the piranha can't get free after swallowing the bait on the hook, the vicious and greedy companion will soon eat all its bones.

Because piranha's teeth are extremely sharp, the aborigines in South America often remove their teeth and make them into sharp arrows to hunt. In addition, the local people also have the custom of water burial. They put the dead into the river to be eaten by piranhas, thinking that their souls would ascend to heaven.