Biggest of the world

Measuring 10 feet (3 meters) long and weighing in at more than 400 pounds (180 kilograms), it's hard to imagine that the arapaima, the largest fish in the Amazon River basin, could ever go missing. But these huge fish are quickly disappearing from Brazilian waterways, according to a new study.

A recent survey of fishing communities in the state of Amazonas, Brazil, found that the arapaima is already extinct in some parts of the Amazon basin. In other parts of the Amazon, its numbers are rapidly dwindling.

However, the researchers also uncovered some good news: In communities where arapaima fishing is regulated, the species is actually thriving, giving the researchers hope that conservation of the species is still possible. [Photos of the Largest Fish on Earth]

Commonly known as pirarucu