Description
Boeseman's rainbowfish is one of the most striking freshwater fish there is: the front half of the body violet-blue and the rear half intense orange or yellow, with the split between the two colours right in the middle. Adult males, about 10 cm long, have a high back and the brightest colours.
It is an active shoaling fish that needs horizontal swimming space. And there is an important nuance: the colours take time. Shops sell grey, dull juveniles; the colour arrives with maturity, after many months.
It comes from lakes of hard, alkaline water, so it fits where Amazonian fish fail: hard tap water, left as it is.
Behavior
Peaceful and shoaling: six minimum, with more females than males. Males display to each other constantly, which is when they show the most colour.
It lives well with active medium-sized fish of hard or medium water: other rainbowfish, barbs, danios, corydoras, bristlenose, clown loaches in a large tank.
Avoid housing it with very slow or shy fish that its activity would stress, and fish of very soft, acidic water.
It is a good jumper: the tank needs a lid.
Habitat
Melanotaenia boesemani lives only in a small lake system on the Vogelkop Peninsula of western New Guinea: Lake Ajamaru and its streams. Clear, hard, alkaline water with plenty of vegetation along the banks.
Because of that tiny range it is listed as endangered, and wild collection is restricted. Shop fish are captive-bred.
In the aquarium it wants a long tank, plants along the sides, open space in the middle and good light, which is what brings out the colour.
Arcoíris de Boeseman is a schooling species, which means that in the wild it lives and moves in large, coordinated groups.
Keep at least 6 individuals so they feel comfortable and their stress level stays low.
Details
🌊 Water parameters
🐠 Minimum tank size
Breeding
A continuous spawner: for weeks the pair leaves a few eggs each day among moss or fine plants, attached by threads.
The parents do not tend them, but they do not go looking for them much either. Moving egg-laden moss to a separate tank gives fry without complications; they need very fine food for the first days.
Beware of mixing it with other rainbowfish: it hybridises easily, and the mixed offspring have the colour of neither parent.
Diet
Omnivorous and undemanding.
- Staple: quality flake or micropellets.
- Supplement: frozen brine shrimp, daphnia and mosquito larvae.
- Plant matter: spirulina flake.
It feeds mostly at the surface and mid-water; what falls to the bottom it rarely picks up.
What about your tank?
Enter your tank's values to see only the compatible species that fit them. Litres apply to fish.
Compatible fish
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7 and 26–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26–30 °C.
They share water: pH 7–8 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.5 and 26–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7 and 26–30 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7.5–8 and 26–28 °C.
They share water: pH 7.5–8 and 26–28 °C.
They share water: pH 7 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.2 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26–27 °C.
They share water: pH 7 and 26–30 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7 and 26–28 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26–28 °C.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–8 and 26–28 °C.
Compatible invertebrates
General guidance based on water parameters, behaviour and known exceptions; always review the individual animals' and aquarium's specific needs.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.5 and 26–27 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26–27 °C.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–7.5 and 26 °C. They only meet at the very edge, so the tank has to hold that value.
They share water: pH 7–8 and 26–28 °C.
They share water: pH 7–8 and 26–28 °C.
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They share water: pH 7–8 and 26–28 °C.
Sources
- FishBaseFroese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication.
- Seriously FishSeriously Fish. Melanotaenia boesemani. Ficha de especie; consultada 2026-08.
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