Called Arapaima in the Guianas, Paiche in Peru, and Pirarucu in Brazil, this relative of the arowana is one of the largest purely freshwater fishes in the world, reaching nine feet and exceeding 400 pounds. They have been overexploited as food fishes, so are vulnerable to extinction. These fast-growing predators surface frequently to take air at the surface. While aquarium visitors may mistake them for Alligator gars, they are not related. Their closest North American relatives are the herring-like Mooneyes and Goldeneyes.