Boesemani rainbowfish
Boeseman's rainbowfish, Melanotaenia boesemani, comes from a very small area of the Ayamaru lakes in West Papua, Indonesia.
A mature male is startling: the front half of the body is deep blue-grey and the rear half orange-red, with the transition falling sharply at the middle.
It reaches around 10 centimetres and lives five to eight years. The wild population is classed as threatened and has been heavily collected, but the species breeds readily in captivity and the fish sold today are overwhelmingly farmed — which is the right ones to buy. Males only develop full colour with age and in the presence of competition, so a single young fish in a shop tank looks nothing like the adult.
- Origin
- Ayamaru lakes, West Papua, Indonesia
- Adult size
- About 10 cm
- Lifespan
- 5–8 years
- Minimum tank
- 150 litres for a group of six or more
- Water
- Hard and alkaline — pH 7.0–8.0
- Temperature
- 24–28°C
3 boesemani rainbowfish photos, newest first
Living with a boesemani rainbowfish
Buy a group, and buy captive-bred. Six or more, with several males, is what produces the colour — males display at each other constantly and a lone male stays drab.
They want hard, alkaline water, which is the opposite of most South American community fish and worth checking against your tap supply before buying.
Give them length. These are active open-water swimmers that cover the tank continuously, so a long tank beats a tall one.
Colour takes time. A juvenile is silver and unremarkable and will not look like the adult for a year or more; shops sell them at that stage and buyers are often disappointed.
They are peaceful and suit a community of similarly sized, similarly active fish. Avoid slow long-finned tankmates that cannot keep up at feeding.
General guidance, not veterinary advice. Individual fishs vary, and anything about a specific animal is a question for a vet who has seen it.
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