Nomorhamphus

Nomorhamphus is a southeast Asian genus of viviparous halfbeaks from streams, rivers and lakes in Sulawesi (Indonesia) and the Philippines. They are all viviparous, producing small clutches of around a dozen fry about long at birth. Females are generally larger than the males. In the largest species, such as Nomorhamphus liemi, the females typically reach about in length, whereas the males reach about in length. Males are also more brightly coloured than the females (often having red, black, or blue patches on their fins). Compared with many other halfbeaks, the lower mandible, or beak, is relatively short, on females in particular barely protruding beyond the length of the upper mandible. The males of some species (e.g., N. ebrardtii) have short, straight beaks, but those of others (e.g., N. liemi) have short beaks that curve downwards forming a shape often compared to a goatee beard by aquarists. N. aenigma is unique within Nomorhamphus because of its lack of lower jaw elongation.

Nomorhamphus feed extensively on small insects, either in the form of aquatic larvae or as flying insects that have fallen onto the surface of the water. They are important predators on insects such as mosquitoes, so play a role in controlling malaria. Nomorhamphus are too small to be of value as food, but they do have some value as aquarium fish.