The red-bellied piranha is a fish that lives in rivers in South America, and it lives in the Amazon River basin. Its belly is red, and its gray body is flecked with silver. It has rows of sharp teeth, and it replaces its teeth through life, one side of the jaw at a time, so it can keep feeding. It grows to about a foot long, and the Los Angeles Zoo says about 12 inches. It can weigh up to 4 pounds, or 1.81 kilograms.

What does a red-bellied piranha eat? It eats other fish, and also shrimp and worms. It eats insects, snails and other mollusks, crustaceans and carrion. In the wild, a good portion of its diet is fins nipped from the tails of larger fish. You may have heard that piranhas only eat meat. In fact, red-bellied piranhas also eat plants and fruit. That makes the menu much longer than many people expect, since red-bellied piranhas eat many kinds of food and fins are only part of the list.

Red-bellied piranhas are scavengers in the Amazon basin. Smaller ones look for food in the day. Larger ones look for food at dawn, in the late afternoon and in the early evening. They live in big groups called shoals. A shoal can have more than a hundred fish in it. You may have heard that piranhas hunt in packs. In fact, they gather in groups for protection rather than hunting their prey in packs. They also make sounds using muscles attached to the swim bladder.

Male red-bellied piranhas build nests in the mud and sand at the bottom of the water. A female can lay thousands of eggs, and the eggs are laid in clusters and stuck to plants growing under the water. Red-bellied piranhas live in the Amazon River basin, the Paraguay-Paraná River basin and rivers of northeastern Brazil, and they tend to travel in schools of 20 or more. They like warm water, about 25 degrees Celsius, and a red-bellied piranha can live about 10 years.

Words to know

• carrion: dead animal food
• crustaceans: shrimp and crabs
• bladder: a body sac
• shoals: fish groups
• scavengers: leftover eaters