Arapaima can weigh more than 28st (180kg) and are highly prized by fishermen
A 10ft (3m) long fish which used to dominate the Amazon river has been fished to extinction in a number of areas, scientists have revealed.
Arapaima populations were found to be extinct in eight of the 41 communities studied, and extremely low on average.
Fishermen were trained to count the fish as part of a large-scale survey.
Researchers concluded that the effects of fishing on tropical fish was worse than previously thought.
Study results are reported in Aquatic Conservation: Freshwater and Marine Ecosystems.
They are air-breathing and come to the surface every five to 15 minutes, making them easy to catch.
Their size means they are highly sought after and are landed by fishermen using harpoons and gillnets.
A century ago the giant fish dominated fisheries in the Amazon but the researchers say overfishing has dramatically reduced their numbers.
Source: BBC Nature News