; superorder Osteoglossomorpha, order Osteoglossiformes)
A small family of freshwater fish that have an elongate, robust body. The single dorsal fin is located close to the small, rounded tail fin and the ventral fins are placed in a mid-ventral (abdominal) position. It is considered a fairly primitive family. Representatives are found in S. America, W. Africa, northern Australia, and south-east Asia. Some species practise buccal incubation. The S. American Arapaima gigas grows to a length of 4.5 m and is one of the world's largest freshwater fish. There are about six species.
Subjects: Zoology and Animal Sciences.