Lorentz River Rainbowfish

Melanotaenia sp. 'Lorentz' is an undescribed rainbowfish collected from the remote Lorentz River and adjacent drainages in West Papua, a region of extraordinary biological diversity protected within the Lorentz National Park, a UNESCO World Heritage Site. Its colouration is notably vivid — a bright yellow-green to lime-green body overlaid with iridescent scale edges, and bold orange-red unpaired fins that create an electrifying contrast with the chartreuse body colour.

As an undescribed species, its exact taxonomic status and relationships remain to be formally resolved. Only a handful of collection events have provided specimens for the hobby, and the captive population is extremely small. Responsible keepers maintain this species in documented groups, avoid hybridisation with related undescribed or described Melanotaenia, and share surplus fish with other verified hobbyists rather than releasing them into anonymous retail chains.

Care requirements are typical for a small to medium Melanotaenia from a highland-influenced river — slightly cooler than lowland species, slightly softer and more acidic water, and high-quality conditions throughout.

Water: pH 6.5–7.5, temperature 22–27°C, soft to moderately hard; cooler than many PNG rainbowfish; clean water essential. Tank: Minimum 120 L; planted aquarium with open swimming space; gentle to moderate current. Feeding: Quality flake and pellets; live daphnia, brine shrimp, and frozen bloodworms for colour intensity. Breeding: Egg scatterer on fine plants; maintain provenance records; share only with responsible hobbyists. Compatibility: Peaceful; suitable with other calm, similarly sized rainbowfish.