My wife and I spent a week in the Peruvian rainforest -- part of the Amazon basin -- about 25 years ago. It was quite an adventure! We lived on a floating houseboat and did day-trips by speed boat into some of the peripheral tributaries of the rainforest.
Many local Peruvians visited us when we were on the houseboat, most of them while fishing in their dug-out canoes. This was during the relatively dry season, before the heavy rains came and the river floods. With the monsoon, the fish leave the confines of the river and forage in the flooded jungle, so they become much harder to catch. The locals were stocking up, preparing for a time when food was harder to come by.
By far the primary fish caught were piranha, the fish of legend. They certainly have sharp teeth, and when fish guts were thrown into the water, the water literally churned with a school of piranha devouring them.
There are several species of piranha, some weighing several pounds, but the most common one we saw was this small one with a pink-orange underbelly, which weighed less than a pound. What they lacked in size, they made up for in volume, with fishermen often catching dozens of them, as you can see below.