Genera: 264 species; 6 families.
Habitat: marine, few needlefish and halfbeaks inhabit brackish and fresh waters; close to the surface.
Ray-finned fish; lack a complete sequence of mitogenomes, many variations in mtDNA; absence of the interhyal, resulting in the upper jaw being fixed or not protrusible; jaw morphologies; they have an elongated lower jaw in juveniles and adults as represented in halfbeaks; needlefish and sauries have both jaws elongated in the adults; the juveniles of most species develop through a "halfbeak stage" before having both jaws elongated; the elongated lower jaw is lost in adults and is lost in most juveniles in the flyingfishes and some halfbeak genera.
Form: streamlined, except Adrianichthyidae.
Food: algae, plankton, smaller animals, other fishes.
Originally, the Adrianichthyidae were included in the Cyprinidontiformes, closely related to the killifish. The flyingfishes are nested within the halfbeaks, and the needlefish and sauries are nested within the subfamily Zenarchopterinae of the family Hemiramphidae, which has been recognized as its own family. The sauries are also nested within the family Belonidae.
• Adrianichthyidae: Ricefish, Medakas; Adrianichthys, Oryzias.
• Belonidae: Needlefish; Ablennes, Belone, Belonion, Petalichthys, Platybelone, Potamorrhaphis, Pseudotylosurus, Strongylura, Tylosurus, Xenentodon.
• Scomberesocidae: Sauries; Cololabis, Scomberesox..
• Exocoetidae: Flyingfishes; Cheilopogon, Cypselurus, Hirundichthys, Prognichthys; Exocoetus; Parexocoetus..
• Hemiramphidae: Halfbeaks; Arrhamphus, Chriodorus, Euleptorhamphus, Hemiramphus, Hyporhamphus, Melapedalion, Rhynchorhamphus.
• Zenarchopteridae: Viviparous halfbeaks; Dermogenys, Hemirhamphodon, Nomorhamphus, Tondanichthys, Zenarchopterus.