Celebese Halfbeak

The Celebese Halfbeak, scientifically known as Nomorhamphus liemi, is a surface-dwelling livebearing fish native to the island of Sulawesi in Indonesia, where it occupies clear, slow-moving streams, forest creeks, and spring-fed pools. Its natural distribution is centered in the South Sulawesi region, particularly within tributaries of the Walanae Basin, the Tosilale River, and nearby upland freshwater systems characterized by dense vegetation, overhanging canopy, and highly oxygenated water. Across these habitats the species remains close to the surface, using its elongated lower jaw to skim insects and tiny invertebrates from the water’s surface.

Adult Nomorhamphus liemi typically reach 3 to 4 inches in length, with a slender, streamlined body, a pointed snout, and a pronounced lower mandible that gives the group its “halfbeak” name. Males display brighter coloration, often showing bright red or orange accents on the fins, while females are larger and more robust. Their posture is characteristically horizontal near the surface, with sudden darting movements when pursuing food or interacting socially. They are peaceful but can show mild sparring among males, especially in the presence of females.

A tank of at least 20 gallons is recommended for a small group, with a long footprint preferred to give them ample surface area. Because these fish inhabit slow, clear waters, the aquarium should have gentle flow, stable surface conditions, and abundant open space at the top of the tank. Floating plants, overhanging stems, or shaded zones help replicate their natural habitat and offer security. A tight-fitting lid is essential, as halfbeaks are powerful jumpers and will readily leap when startled or during social interactions.

Water parameters should reflect their native Sulawesi streams, with temperatures between 75 and 82°F, a pH from 7.0 to 8.0, and moderately hard to hard water being ideal. They are sensitive to sudden changes in temperature and surface agitation, and they thrive best in mature aquariums with stable, well-oxygenated water. Clean conditions are important, as halfbeaks react poorly to accumulating waste or fluctuating parameters.

Feeding Nomorhamphus liemi is simple, as they are primarily micropredators. In nature they hunt small insects, larvae, and drifting invertebrates at the surface. In the aquarium they readily take floating micro-pellets, crushed floating foods, small live insects such as fruit flies, baby brine shrimp, mosquito larvae, and fine freeze-dried foods. They rarely take sinking items, so surface-oriented feeding is crucial to maintaining good body condition.

Celebese Halfbeaks are peaceful community fish when kept with similarly gentle species that do not compete aggressively at the surface. Avoid fast, boisterous fish that may out compete them or cause stress. Ideal companions include calm mid-water schooling fish and peaceful bottom-dwellers. Mild territorial interactions between males are normal, especially when females are present, but serious aggression is uncommon in well-spaced groups.

Breeding Nomorhamphus liemi is achievable in captivity, as it is a livebearing species. Females give birth to fully formed young after a gestation period of several weeks. Newborn fry stay near the surface and will accept powdered foods, baby brine shrimp, and infusoria. Adult fish may prey on fry, so dense floating cover or a separate rearing space improves survival rates.

Nomorhamphus liemi, the Celebese Halfbeak, is a graceful, surface-dwelling livebearer that brings unique behavior and subtle beauty to the aquarium, thriving in calm, clean, well-oxygenated tanks with gentle flow and peaceful tankmates.