Arapaima gigas
Known as the pirarucu in Brazil and the paiche in Peru, this South America giant is one of the largest freshwater fish in the world. Some reach lengths of more than 10 feet (3 meters) and weigh upward of 400 pounds (180 kilograms). Large megafish like these have become rare worldwide due to heavy fishing. The arapaima is the focus of several conservation projects in the Guianas.

The arapaima is an air-breathing fish that plies the rain forest rivers, lakes and swamps. They have a wide, scaly, gray body and a tapered head. Though arapaimas can stay underwater for 10 to 20 minutes, they tend to remain near the water’s surface, where they hunt and emerge often to breathe with a distinctive coughing noise. They survive mainly on fish but are known to occasionally grab birds close to the water’s surface.

The Amazon’s seasonal floods have become part of the arapaima’s reproductive cycle. During low-water months (February to April) arapaimas construct bottom nests and females lay eggs. Young begin to hatch as rising water levels provide them with flood conditions in which to flourish. Adult males play an unusual reproductive role by incubating tens of thousands of eggs in their mouths, guarding them aggressively and moving them when necessary.