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

Boeseman's Rainbowfish are striking, deep-bodied fish with a distinctive two-tone colour pattern. Mature males typically show an iridescent blue or violet front half that transitions sharply into orange, copper or yellow across the rear of the body. Their scales reflect the light strongly, making a healthy group especially eye-catching as it moves through the aquarium.

They are active, peaceful schooling fish with a confident but generally non-aggressive temperament. Males often display beside one another, extending their fins and intensifying their colours without causing serious injury. Their lively behaviour is best appreciated in a group, where they spend much of their time in the middle and upper areas of the water.

In the wild, this species is associated with the Ayamaru Lakes and nearby waterways, where it inhabits open freshwater environments bordered by vegetation. The lake system contains clear, alkaline water and varied margins that provide both swimming space and shelter.

Boeseman's Rainbowfish became popular in the aquarium hobby because of the exceptional colouration developed by mature males. Their wild populations have been affected by a restricted natural range and habitat pressures, so captive-bred fish are by far the usual choice for aquariums.

Boeseman's Rainbowfish are native to the Ayamaru Lakes system in West Papua, Indonesia, on the island of New Guinea. They occur in clear, mineral-rich freshwater lakes and their connected streams.

A group should be kept in an aquarium of at least 150 litres, with a footprint of around 120 cm by 40 cm to provide the long swimming run this active species needs. Use open central swimming space with dense planting, wood or rockwork around the sides and rear for cover. A dark sand or fine-gravel substrate can enhance their colours, while a secure lid is advisable because active rainbowfish may jump. Good filtration, strong oxygenation and regular maintenance are important for this naturally active species.

Up to 12 cm (4.7 inches) in total length; males are usually larger and deeper-bodied than females, which commonly reach around 8–10 cm (3.1–3.9 inches).

They are omnivores that benefit from a varied diet of quality flakes and small pellets supplemented with frozen or live foods such as brine shrimp, daphnia, bloodworm and mosquito larvae. Small amounts of vegetable matter, including spirulina-based foods, help provide a balanced diet. Offer appropriately sized portions several times a day when possible, especially to growing fish.

Boeseman's Rainbowfish are peaceful community fish, although their energetic swimming can overwhelm very timid species. Suitable companions include other similarly sized rainbowfish, peaceful barbs, danios, larger tetras, Corydoras, peaceful loaches and many calm gouramis. Avoid housing them with aggressive cichlids, fin-nipping species or very slow-moving fish with long flowing fins, and do not combine them with fish small enough to be viewed as prey.

Boeseman's Rainbowfish are egg scatterers that readily spawn when well conditioned with varied, nutritious foods. Provide fine-leaved plants or a spawning mop, where a female can deposit small adhesive eggs over several days. Adults may eat the eggs, so remove the mop or transfer the eggs to a separate rearing container. The eggs usually hatch after about a week, and the tiny fry initially need infusoria-sized foods before progressing to larger fry foods.

Males are generally larger, more robust and much more intensely coloured, with a deeper body and longer, more pointed dorsal and anal fins. Females are usually smaller and slimmer, with less dramatic blue-and-orange contrast and a more subdued overall appearance.