Boeseman's Rainbowfish

Melanotaenia boesemani

Rainbowfish
Reviewed by Guidarium Editorial DeskUpdated April 28, 2026

An incredibly popular and active schooling fish endemic to the Ajamaru Lakes in West Papua, Indonesia (currently listed as Endangered in the wild by the IUCN due to overfishing and habitat loss, though commercially captive-bred). Famous for the mature male's spectacular blue and orange split-coloration. They require long tanks for active swimming, excellent oxygenation, and warm, hard, alkaline water to thrive.

Boeseman's Rainbowfish At a Glance

Adult Size10 cm
Body ShapeCompressed
Growth RateModerate
TemperamentPeaceful
Water TypeFreshwater Only
Flow PreferenceModerate
Waste OutputMedium
StockingSchool of 6+

Boeseman's Rainbowfish Tank Requirements

Minimum Volume200 L
Minimum Length120 cm
FlowModerate
Water TypeFreshwater Only
Must-Haves in the Tank
Plants - lighly covered
Stocking calculator

Will Boeseman's Rainbowfish fit in your tank?

Care guides tell you what Boeseman's Rainbowfish needs, the next question is whether your tank can safely provide it. Test Boeseman's Rainbowfish against your tank size, maintenance needs, and the fish you already keep before you buy.

Boeseman's Rainbowfish
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Boeseman's Rainbowfish Water Parameters

Temperature2630°C
pH78.1
Hardness919 dGH

Boeseman's Rainbowfish Temperament & Compatibility

Aggression LevelPeaceful
2/10
Where They Swim
Surface
Mid-level
Bottom
Stocking Guidelines
Keep at Least6 fish
Max per TankNo limit
Can Live Alone?No — needs a group
Behavior Traits
Hyperactive / Fast SwimmerAggressive Eater (Starves shy fish)Jumper (Lid Required)

Boeseman's Rainbowfish Varieties

Each variety inherits the species defaults above. Only differences are highlighted.

Male

Adult males develop a highly arched back (deep body) and the iconic two-tone coloration: a bluish-purple front half and a vibrant orange-yellow rear. They continuously display to females and spar harmlessly with rival males. Best kept in a ratio of 1 male to 2 females, or in large groups.

Differs in 1 trait from base species

Also known as: Show Male, Adult Male

Adult Size11 cm

Female

Females are slightly smaller, more streamlined, and have subdued coloration (mostly silver/grey with yellowish fins and faint horizontal stripes). Keeping a proper female-heavy ratio reduces harassment stress and brings out the males' most intense display colors.

Differs in 1 trait from base species

Also known as: Female

Adult Size9 cm

Unsexed Juvenile

Most commonly found in stores at 3-5cm. Juveniles of both sexes are relatively colorless and silvery. It takes several months of high-quality diet and pristine water conditions for males to develop their characteristic deep body shape and dramatic colors.

Differs in 1 trait from base species

Also known as: Baby, Juvenile

Adult Size4.5 cm

Boeseman's Rainbowfish Care Guide Summary

The Boeseman's Rainbowfish, scientifically known as Melanotaenia boesemani, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 10 cm and have a compressed body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a medium level of biological waste.

To thrive, the Boeseman's Rainbowfish requires a freshwater only aquarium with a minimum volume of 200 litres and a tank length of at least 120 cm. Water temperature should be maintained between 26°C and 30°C, with a pH range of 78.1 and a general hardness of 919 dGH. A moderate water flow is preferred.

The Boeseman's Rainbowfish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 3 varieties: Male, Female, and Unsexed Juvenile. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.

Boeseman's Rainbowfish Habitat Setup

When setting up an aquarium for the Boeseman's Rainbowfish, a moderate water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include light plant coverage for partial shade. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.

Boeseman's Rainbowfish Compatibility Notes

Classified as peaceful, the Boeseman's Rainbowfish is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, shy or slow-feeding tankmates may be outcompeted at feeding time and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.

Who Boeseman's Rainbowfish Is Actually For

Boeseman's Rainbowfish is best for a fishkeeper who wants a species that can settle into a calmer community setup and can provide a keeper who can commit to a proper group of at least 6. It makes the most sense for a hobbyist who will actually build around its needs, especially plants.

The most common mistake is buying Boeseman's Rainbowfish for looks first and only later discovering how its adult size, behavior, or bioload changes the whole tank plan. Another frequent problem is underestimating its social needs. A token pair or trio often behaves very differently from a real group.

Boeseman's Rainbowfish Recommended Tank Sizes

Standard aquarium sizes that meet the minimum volume and length requirements for Boeseman's Rainbowfish.

Show 5 more tank sizes

Frequently Asked Questions About Boeseman's Rainbowfish

How big does Boeseman's Rainbowfish get?

Boeseman's Rainbowfish (Melanotaenia boesemani) typically reaches a maximum adult size of approximately 10 cm. They have a compressed body shape and a moderate growth rate.

What tank size does Boeseman's Rainbowfish need?

A minimum aquarium volume of 200 litres and a tank length of at least 120 cm are recommended for Boeseman's Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.

What water parameters does Boeseman's Rainbowfish need?

Boeseman's Rainbowfish thrives in freshwater only conditions with a temperature range of 26–30°C, a pH between 7 and 8.1, and a general hardness of 9–19 dGH. A moderate water flow is preferred.

Is Boeseman's Rainbowfish peaceful or aggressive?

Boeseman's Rainbowfish is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.

How many Boeseman's Rainbowfish should be kept together?

Boeseman's Rainbowfish is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.

Does Boeseman's Rainbowfish have any special tank requirements?

Yes. Boeseman's Rainbowfish benefits from plants - lighly covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.

Does Boeseman's Rainbowfish need a lid on the tank?

Yes. Boeseman's Rainbowfish is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.

Editorial Review

Guidarium Editorial Desk

Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.

Last reviewed
April 28, 2026
Last updated
April 28, 2026
Issues or corrections?
Contact the editorial team

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