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Passport
- Family
- Rainbowfish
- Grows to
- 8 cm (3.1")
- Lives
- 5–8 years
- Temperament
- Peaceful
- Care
- Beginner
- Swims
- Mid-water
- Keep
- In a group of 6 or more
- Water
- 27–30 °C (81–86 °F)
Indonesia
Care requirements
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On record for Boeseman's Rainbowfish: adult size, lifespan, minimum tank, temperature, ph, hardness, minimum group, diet, care level, swim level, tank length.
A figure that is not on record is left out rather than guessed. One marked Suggested comes from keeping knowledge rather than a page.
- Minimum tank 110 L / 29.1 US gal
- pH 7–8
- Hardness 10–20 dGH
- Diet omnivore
- Tank length 120 cm minimum
Care notes written from general aquarium knowledge, not from the cited sources.
About
Boeseman's rainbowfish are painted in two halves. The front is a deep blue-purple, the back a hot orange-yellow, and the transition happens abruptly around the middle of the fish as though someone dipped it. Nothing else in fresh water looks like that.
Only the males do it, and they take their time — a young Boeseman's is a plain silver thing, and the colour arrives over a year or more. Buying juveniles requires faith.
They come from a couple of lakes in West Papua, where the wild population has been under real pressure from collection. Tank-bred stock is widely available and is the right choice.
Tank setup
Give your Boeseman's a long tank. They're active, deep-bodied fish that cruise constantly, and length matters more than volume.
Keep a group with several males. Males display at each other continuously — flaring, posturing, colour flashing — and that competition is what drives the colour. A lone male stays dull.
Keep the water hard and alkaline. This surprises people: rainbowfish generally prefer harder water than the South American community fish they're sold beside, and soft acidic water suits them poorly.
Plant the sides and back and leave a long open channel. They need the run.
Cover the tank. They're strong swimmers and they jump.
Feeding
Boeseman's are omnivores with good appetites and small mouths for their body size.
Feed a quality flake or small pellet as the base, with frozen and live food regularly. Colour responds strongly to diet, and carotenoid-rich foods deepen the orange.
Feed at the surface and in mid-water. They rarely take much from the bottom.
Avoid: large pellets, which they struggle with despite their size, and avoid a plain dried diet if you want the colour to develop.
Filtration and flow
Give them decent flow and good oxygenation. They're powerful swimmers used to open, well-moved water.
Filter properly for a fish of this size kept in a group. They're substantial and they eat well.
Hard, alkaline, well-oxygenated water with regular changes is the whole requirement.
With plants
Boeseman's rainbowfish are safe with plants and won't damage them.
Plant heavily at the back and sides. The contrast between dense green and an orange-and- purple fish is worth engineering deliberately.
Their preference for harder water suits vallisneria, java fern and anubias particularly well.
Health
They're hardy and long-lived in suitable water, and problems are uncommon.
Colour is the gauge for males. A dull male is usually young, alone, or kept in soft water rather than sick.
Jumping is the main hazard. Keep the tank covered.
Breeding
Rainbowfish spawn continuously rather than in single events. A conditioned pair releases a few eggs each morning over weeks, attaching them by fine threads to fine-leaved plants or spawning mops.
That makes collection easy: put a mop in, lift it out every few days, and move it to a rearing container. The adults eat eggs but not with much determination.
Fry are small and hang at the surface, which is a trap — they need food right at the top, and infusoria or a very fine dry food before they can take baby brine shrimp. Losing broods to starvation in the first week is the usual failure.
Tank mates
Avoid8
- Least Killifish Boeseman's Rainbowfish grows to 8 cm against Least Killifish at 2 cm, big enough to eat it.
- Scarlet Badis Boeseman's Rainbowfish grows to 8 cm against Scarlet Badis at 2 cm, big enough to eat it.
- Common Goldfish Common Goldfish is not safe with Boeseman's Rainbowfish: common goldfish and rainbowfish are a bad pairing.
- Demasoni Cichlid Demasoni Cichlid is not safe with Boeseman's Rainbowfish: african cichlids and rainbowfish are a bad pairing.
- Electric Yellow Lab Boeseman's Rainbowfish and Electric Yellow Lab do not mix: african cichlids and rainbowfish are a bad pairing.
Only with care10
- Convict Cichlid Convict Cichlid is noticeably larger than Boeseman's Rainbowfish and may bully it or outcompete it at feeding time.
- Jewel Cichlid Jewel Cichlid is noticeably larger than Boeseman's Rainbowfish and may bully it or outcompete it at feeding time.
- Chinese Algae Eater Chinese Algae Eater is aggressive and Boeseman's Rainbowfish is peaceful.
- Betta Betta is a risk to Boeseman's Rainbowfish: betta (male) and rainbowfish are a pairing to watch.
- Clown Killifish Boeseman's Rainbowfish is a risk to Clown Killifish: killifish and rainbowfish are a pairing to watch.
No conflict is recorded with the other 88 species in the database, so nothing to flag. 2 species are not covered at all, so they could not be judged either way.