Osteoglossids are basal (primitive) fish from the lower Tertiary and are placed in the actinopterygiid order Osteoglossiformes. As traditionally defined, the family includes several extant species from South America, one from Africa, several from Asia, and two from Australia. Today Arapaimidae is often regarded as a separate family, which includes the arapaimas and the African arowana.  Consequently, the South American genus Osteoglossum, and the Asian and Australian genus Scleropages are the only extant general that remain in the osteoglossid family. Arapaimidae and Osteoglossidae split about 220 million years ago (Mya), during the Late Triassic.

Within Osteoglossidae, the South America Osteoglossum arowanas diverged from the Asian and Australian Scleropages arowanas about 170 Mya, during the Middle Jurassic.

The Osteoglossidae are the only exclusively freshwater fish family found on both sides of the Wallace Line.[6] This may be explained by the theory that Asian arowanas (S. formosus) diverged from the Australian Scleropages, S. jardiniiand S. leichardti, about 140 Mya, making it likely that Asian arowanas were carried to Asia on the Indian subcontinent

Several species of osteoglossids exhibit parental care. They build nests and protect their young after they hatch. All species are mouthbrooders, the parents holding sometimes hundreds of eggs in their mouths. The young may make several tentative trips outside the parent's mouth to investigate the surroundings before leaving permanently.