Hemiramphus marginatus belongs to the halfbeaks. This family includes both marine as well as freshwater species and is recognizable by the characteristically enlarged lower jaw.
This halfbeak can be found in coastal waters rich in sea grasses and on sand flats, where it forms schools. The animals feed mainly on algae and sea grasses as well as plankton and the occasional small crustacean/fish fry. They reproduce in and around estuaries.
With 30 cm total length Hemiramphus marginatus is far too big for typical aquaria, especially considering that these schooling fish remain for the most part directly below the water line and need a correspondingly large surface area. With halfbeaks there is also the constant danger that collisions with the glass or the rough handling during catching and shipping result in typically fatal mandibular fractures.