Arapaima is a genus of freshwater fish found in the Amazon Basin of South America. The largest species, Arapaima gigas, is one of the largest freshwater fish in the world, reaching up to 3 meters (10 feet) in length and weighing up to 200 kilograms (440 pounds). Arapaimas have a long, cylindrical body shape and are covered in large, bony scales. They have a primitive lung, which allows them to breathe air, and they need to surface regularly to do so.

Arapaimas are apex predators and feed on fish, crustaceans, and even small mammals and birds that fall into the water. They are also important to local communities as a source of food and income. Due to overfishing and habitat destruction, some species of arapaima are considered endangered. However, conservation efforts have been successful in some areas, and there are now protected areas where arapaima populations are thriving.