any of several heavy-bodied tropical river fishes, family Osteoglossidae, covered with large, hard, mosaic-like scales except on the head. The largest member of the family, the arapaima, paiche, or pirarucu (Arapaima gigas) of South America, may be about 2.4 metres (8 feet) long and weigh about 91 kilograms (200 pounds). It is a valuable, sinuous green fish with a reddish tail. Other bony tongues are the African Clupisudis (also known as Heterotis), the South American arawana (Osteoglossum bicirrhosum), and two species of the East Indian genus Scleropages.