They are a geographically widespread and numerically abundant family of epipelagic fish inhabiting warm waters around the world.

On the one hand, there is little question that they are most closely related to three other families of streamlined, surface water fishes: the flyingfishes, needlefishes, and sauries.

[7] On the other hand, recent studies have demonstrated that rather than forming a single monophyletic group (a clade), the halfbeak family actually includes a number of lineages ancestral to the flyingfishes and the needlefishes.

[5] Within the subfamily Hemiramphinae, the "flying halfbeak" genus Oxyporhamphus has proved to be particularly problematic; while morphologically closer to the flyingfishes, molecular evidence places it with Hemiramphus and Euleptorhamphus.

However, this hypothesis has awkward implications for how the morphological evolution of the group is understood, because the fused pharyngeal plate has been considered reliably diagnostic of the halfbeak family.

[5] In fact the unequal lengths of the upper and lower jaws of halfbeaks appears to be the basal condition, with needlefish being relatively derived in comparison.

[5] As is typical for surface dwelling, open water fish, most species are silvery, darker above and lighter below, an example of countershading.

Combined with their streamlined shape and the concentration of fins towards the back (similar to that of a pike), these adaptations allow halfbeaks to locate, catch, and swallow food items very effectively.

[11] They are in turn eaten by many ecologically and commercially important fish, such as billfish, mackerel, and sharks, and so are a key link between trophic levels.

These fish school near the surface at night but swim closer to the sea floor during the day, particularly among beds of seagrasses.

[7] They are usually egg-layers and often produce relatively small numbers of fairly large eggs for fish of their size, typically in shallow coastal waters, such as the seagrass meadows of Florida Bay.

[15][18] The southern sea garfish Hyporhamphus melanochir grows rapidly at first, attaining a length of up to 30 cm (12 in) in the first three years, after which point growth slows.

[15] This species lives for a maximum age of about 9 years, at which point the fish reach up to 40 cm (16 in) and weigh about 0.35 kg (0.77 lb).

[14] Halfbeaks are caught by a variety of methods including seines and pelagic trawls, dip-netting under lights at night, and with haul nets.