© Thomnight / CC BY-SA 2.0 deLake Kutubu Rainbowfish
The Lake Kutubu Rainbowfish is an endemic species found only in Lake Kutubu and its outflow, the Soro River, in Papua New Guinea. Its sky-blue back and gleaming silvery-white underside create a striking contrast that becomes even more vivid when the fish are kept together in a group. It thrives in hard, slightly alkaline water and grows to a robust size of up to 12cm. While considered suitable for intermediate keepers, its care becomes manageable once the water chemistry it prefers is understood, making its rainbow-like shimmer a rewarding long-term feature of any tank.
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Apply as a breederLake Kutubu Rainbowfish key facts
- Care level
- Intermediate
- Lifespan
- 5-8 years
- Size
- Up to 12cm SL
- Temperature
- 20〜25℃
- Diet
- Dried, frozen and live foods
- Tank
- Seriously Fish suggests a 120 x 30cm base of about 108 litres. It is active, so use a long tank with densely planted areas alongside open swimming space, and keep water movement to a minimum.
- Water Temperature & Quality
- Seriously Fish gives 20-25C, pH 7.0-9.0 and 10-20 dGH and warns against soft, acidic water. FishBase records pH 7.0-8.0, 9-12 dH and 20-24C in the wild.
- Tank Mates
- Peaceful but quick enough to unsettle small or slow fish. Similar-sized rainbowfish, characins, danios, barbs and Corydoras suit it, and its water requirements also allow many Rift Lake cichlids.
- Diet & Feeding
- Omnivorous and unfussy, taking dried, frozen and live foods. Regular frozen and live feeds improve its colour.
- Breeding & Spawning
- Spawning is not difficult, the fish being an egg scatterer, though the fry take some effort. Use a spawning tank at about pH 7.5 and 22-24C with java moss or spawning mops; the female lays a few eggs daily.
- Health & Notes
- Juveniles on sale look plain and the adult blue develops with growth. Small groups make the fish timid, so keep six to eight or more. Overfishing and habitat degradation have led the IUCN to list it as Endangered; it is not covered by CITES.
About Lake Kutubu Rainbowfish
Discover the Lake Kutubu Rainbowfish (Blue Rainbow), a sky-blue and silvery endemic species from Papua New Guinea, and key points for keeping it well.
7 things to know before welcoming a Lake Kutubu Rainbowfish
1Hard, Slightly Alkaline Water
Mimicking its native Lake Kutubu, maintaining hard, slightly alkaline water is fundamental to good coloration and health. Without the right water chemistry, the fish's characteristic sky-blue and silvery-white shine may not fully develop. Check in advance how you'll adjust water hardness and pH with filter media or additives.
2Keeping in Groups Enhances Color
This species shows better coloration when kept in a group rather than alone. Preparing a tank large enough to house several individuals together beforehand will help bring out its natural beauty.
3Grows Up to 12cm
Adults can grow up to about 12cm. Since this species is best kept in groups, plan for a tank with enough capacity to accommodate their adult size along with several tankmates.
4Suited to Intermediate Keepers
This species is generally considered suitable for intermediate keepers. Prior experience with basic water quality management will make the transition smoother. First-time keepers should build up some foundational knowledge before bringing one home.
5An Endemic PNG Species
As a species found only in Lake Kutubu and the Soro River, recreating aspects of its native environment is key to successful keeping. Avoid sudden changes in water quality or temperature and maintain a stable environment.
6Choosing Tankmates
Being generally peaceful, it's best to avoid pairing this species with aggressive tankmates. Combining it with other species that also prefer harder water simplifies overall tank management.
7Cycling the Tank Beforehand
Since this species is typically introduced as a group, it's important to fully cycle the tank's filtration before their arrival. Because several fish are added at once, make sure conditions are stable enough to avoid sudden water quality shifts.
Frequently asked questions about Lake Kutubu Rainbowfish
- Q.Can beginners keep the Lake Kutubu Rainbowfish?
- A.It's classified as suitable for intermediate keepers. Having some basic knowledge of water quality management helps a lot, so first-time keepers are encouraged to learn the fundamentals before getting started.
- Q.How many should be kept together?
- A.This species colors up better when kept in a group rather than alone. It's worth planning your tank size and numbers so you can house several together.
- Q.How large does it grow?
- A.Adults reach a maximum size of around 12cm. Since it's best kept in groups, make sure to prepare a tank with sufficient capacity.
- Q.How should water quality be managed?
- A.Following its native Lake Kutubu conditions, the basic approach is to maintain hard, slightly alkaline water. Avoid sudden changes and aim for a stable environment.
- Q.Is this species subject to any regulations?
- A.The Lake Kutubu Rainbowfish is not subject to CITES.
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