Bleher's Rainbowfish Care Guide - Aquarium Setup, Diet & Breeding

Bleher's Rainbowfish are elegant, laterally compressed fish with a deep-bodied profile and a distinctive iridescent sheen. Mature males can display vivid blue-green colouring toward the front of the body, warmer orange or reddish tones along the flanks, and contrasting darker markings on the fins. Colour intensity varies with mood, age, sex and social position.

These are active, peaceful schooling fish that spend much of their time in the middle and upper levels of the aquarium. Males may display to one another by extending their fins and intensifying their colours, but these contests are generally harmless when the group has enough space and females are present.

In the wild, they are associated with flowing, well-oxygenated streams, often over gravel, sand and rocky substrates. Their streamlined shape and strong swimming ability reflect life in clear waterways with regular movement and plentiful cover at the margins.

Bleher's Rainbowfish were named after the German explorer and aquarist Heiko Bleher. They are prized in the hobby for their lively behaviour, attractive adult colouration and suitability for a peaceful community aquarium with other appropriately sized fish.

Bleher's Rainbowfish come from clear streams and tributaries of the Mamberamo River system in northern Papua New Guinea, on the island of New Guinea. They inhabit the freshwater waterways of Oceania.

A group should have at least a 120-litre aquarium, with a footprint of about 90 by 35 cm or larger to provide a useful length of open swimming space. Use a secure lid, gentle to moderate current and efficient filtration with good oxygenation. A sandy or fine-gravel substrate, smooth stones, hardy plants around the edges and some floating cover create a natural layout while leaving the centre open. Regular maintenance and stable, clean water are especially important for this active stream-dwelling species.

Males reach up to about 10 cm (4 inches), while females are usually slightly smaller at around 8–9 cm (3.1–3.5 inches).

Offer a varied omnivorous diet of quality small pellets or flakes supplemented with frozen or live foods such as daphnia, brine shrimp, mosquito larvae and bloodworms. They also benefit from occasional vegetable matter, including spirulina-based foods. Feed small portions once or twice daily, ensuring that all fish can eat without excessive competition.

Bleher's Rainbowfish can share a community aquarium with other peaceful, similarly sized rainbowfish, larger tetras, danios, rasboras, peaceful barbs, Corydoras and smaller peaceful loaches. Choose tankmates that appreciate active open swimming space and comparable water conditions. Avoid very timid fish, slow species with long flowing fins, aggressive cichlids and fin-nipping tankmates; very small fish or fry may also be eaten.

Bleher's Rainbowfish are egg scatterers that can be bred in a separate breeding aquarium. Condition a group with varied, protein-rich foods, then provide spawning mops or fine-leaved plants for the eggs to be attached to. Spawning usually occurs over several days, with the adults moved or the mop transferred to a rearing tank because the eggs and newly hatched fry may be eaten. Feed free-swimming fry infusoria or commercial fry food before introducing newly hatched brine shrimp.

Males are generally larger, deeper-bodied and much more vividly coloured than females, especially once mature. They also tend to develop more extended fins and show stronger displays, while females are usually slimmer and more subdued in colour.