On a warm, humid morning, along the Içana River in Brazil’s upper Rio Negro Basin, researchers observed a group of Baniwa men heading to the river to check the fishing traps they left in shallow, fast-moving waters. Slightly further downstream, a group of giant otters (Pteronura brasiliensis) was also hunting. They stayed in the water by the riverbank, their heads popping through the surface and dipping back down like a wild version of the arcade game Whack-A-Mole. One resurfaced with a striped fish held between its front paws before it climbed onto the bank to eat. The sound of it eating carried across the water; sharp cracks as it worked through the bones and wet chomps as it tore through scales and flesh. The otters’ feeding site along the bank was littered with fish bones and reeked of feces. “They’re almost impossible to ignore,” Jansen Zuanon, ecologist and fish specialist who contributed to a 2026 study about Baniwa people and otters, told Mongabay. Giant otters tend to live in groups of between nine and 12 family members. Image by Allan Hopkins via Flickr (CC BY-NC-ND 2.0). The Içana flows into the Rio Negro, a major tributary in the Amazon with dark, tea-colored, naturally acidic water. Its rivers and tributaries are home to diverse fish species — though they are not especially abundant. For the Indigenous Baniwa people, who live along the Içana’s banks and tributaries in northwestern Brazil near the Colombian border, fishing is an essential source of protein. But…This article was originally published on Mongabay