Osteoglossiformes (subclass Actinopterygii, superorder Osteoglossomorpha) An order of freshwater fish that includes several families with fossil relatives. All have a single, soft-rayed, dorsal fin, low-placed pectoral fins, small, midventral, pelvic fins, and a long-based anal fin. The order includes the Notopteridae (featherback), Hiodontidae (mooneye), Osteoglossidae (bony tongue), and Pantodontidae (butterfly fish).

Mormyriformes (subclass Actinopterygii, superorder Osteoglossomorpha) An order of primarily nocturnal freshwater fish that have small eyes and mouth and varying body profile. Several genera (e.g. Mormyrus and Gymnarchus) have electric organs capable of producing weak electric discharges.