Hemirhamphodon is a genus of halfbeaks in the family Zenarchopteridae, native to Sundaland forest streams in Indonesia, Malaysia, Singapore, and Thailand, typically in the soft, tea-colored blackwater draining peat-swamp and rainforest catchments. The atlas covers 9 species, from about 1.5 in to 4 in, and like the family's other halfbeaks they carry a strikingly elongated lower jaw used to snap up insects and other small prey from the water's surface. Unlike egg-laying halfbeaks elsewhere, Hemirhamphodon species are livebearers, fertilizing internally and releasing free-swimming young rather than laying eggs.
These are specialist rather than mainstream aquarium fish, kept mostly by blackwater and livebearer enthusiasts who can offer the soft, acidic, tannin-stained water and steady supply of small live foods the group generally needs to settle in and breed. Named species in the trade include the goldspotted halfbeak (H. chrysopunctatus), forest halfbeak (H. pogonognathus), red-striped halfbeak (H. kapuasensis), and Borneo redline halfbeak (H. tengah). Most of the genus is currently rated Least Concern, with one Vulnerable and one Near Threatened species, a relatively secure picture for now, though the Bornean and Sumatran peat-swamp habitats the genus depends on are under mounting pressure from logging and land conversion regionwide.