There are 20 species of piraña in a rainbow of colors, though the most common in Peru is the red-belly piraña, which is crimson on the bottom and silvery-green on the sides. This piraña hunts in schools and eats whatever it can: mollusks, crustaceans, insects, birds, lizards, amphibians, rodents, baby caiman, and other pirañas. During the Amazon’s high-water months, they also eat submerged fruit.
Contrary to the pop culture image of pirañas devouring people in a bloody maul of frothy water, these fanged creatures rarely bother humans, as proven by troops of Amazon children that play each day in the river Nobody remembers a human being killed by a piraña, although plenty have been viciously nipped.
If you swim in a jungle river, avoid the warm, still waters favored by these fish. Piraña, like sharks, are attracted by blood and splashing in the water. They can become especially aggressive when food is scarce, such as when trapped in a drying lake. They are most active at dawn and dusk and sleep at night.
A must-do activity at most jungle lodges in the Peruvian Amazon  is piraña fishing. You will be provided with a string, a hook, and a chunk of red meat. Just plunk the baited hook into the still waters of nearly any Amazon backwater and presto! Once you feel the aggressive tug of these palm-sized fish, the fun has just begun.
Before you grab hold of your catch, ask your guide to do so instead. With a bulldog face, powerful lower jaw, and a set of razor-sharp teeth, these little creatures will nip at anything in reach and cause a nasty bite. So leave the fish handling to the guide.