Size: Up to 10 feet
Habitat/Range: Freshwater rivers of South America's Amazon Basin
The arapaima, also called the pirarucu, is one of the largest freshwater fish in the world, and can breathe air. The ability to breathe air is a common adaptation for fish species that often live in oxygen depleted water. While they acquire most of their oxygen via gills, they can also absorb oxygen from a special organ inside the arapaima's mouth by gulping air at the surface. The Amazon River seasonally floods the forests providing additional habitat and food resources for many fish species. Conversely, the dry season reduces the same habitats, often forming isolated lakes where food and oxygen are quickly depleted. The arapaima lays its eggs in a nest during the dry season so that the eggs hatch with an abundance of food during the rainy season.