It includes the South American arapaimas of the Amazon and Essequibo basins and the African arowana (Heterotis niloticus) from the watersheds of the Sahelo-Sudanese region, Senegal, Gambia, and parts of Eastern Africa.

[2] Arapaimides, along with other osteoglossomorphs, are of phylogenetic and evolutionary interest due to their trans-oceanic distribution, excellent fossil record, and position as one of the oldest living teleost lineages.

Arapaimides are characterized by elongate, slender bodies with large scales and long dorsal and anal fins positioned close to a short caudal peduncle.

[10][11] Arapaima is typically a top-water fish predator, while Heterotis is a benthic mud-filterer primarily feeding on phytoplankton and small crustaceans with their suprabranchial organ.

However, minimum ages of intercontinental clades and presence of marine forms in the fossil records imply that ancestral trans-oceanic dispersal is possible.

Tests of these hypotheses are currently inconclusive as they are dependent on an a priori calibrated age of crown-group Teleostei, about which fossil and molecular evidence disagree.