Arapaima (Arapaima gigas), also known as Pirarucu because of the bony teeth on its tongue. The largest adult Arapaima can grow up to six meters and weigh up to 100 kilograms, making it one of the largest freshwater fish in the world. They feed mainly on fish, shrimps and frogs, but also occasionally on snakes, turtles and insects. They can live 15 to 20 years.