Should I buy it?
Turquoise / Lake Kutubu rainbowfish
Melanotaenia lacustris
Also known as: turquoise rainbowfish, turquoise rainbow, lake kutubu rainbow
A deep-bodied 12 cm rainbow with brilliant blue-green scales. Needs a school in a long tank; full colour requires competitive male display.
Turquoise / Lake Kutubu rainbowfish tank mates · 200L tank size hub
peaceful · intermediate care
Sources & confidencehigh · partially verified · beginner: caution
Checked against several solid care sources that mostly agree. Numbers here are a careful starting point. Your tap water, tank size, and habits decide the rest. How we evaluate.
Best for: Planted community tanks 200L or more with a school of eight and at least 120 cm of forward run.
Avoid if: Tanks under 150 cm in length, or setups with fragile nano fish.
Common mistakeKeeping one or two turquoise rainbowfish because the bag looked bright is how keepers invent dull adults. Full colour needs competitive male display in a school of six or more with real length. A pair in a short tank never shows the fish people paid for.
Top things that go wrong
- Group welfare — not a solo display fish. Plan at least **6** together for normal behaviour; smaller groups often mean stress, colour loss, or nipping depending on species.
- Shrimp & snails. Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
What most shops don't tell you
- 1.Myth: turquoise rainbowfish stay tiny and suit any community nano. Reality: they grow into active midwater swimmers that need length, a real school, and room to show colour — understocked or cramped tanks mute them and turn a show fish into a stressed jumper.
- 2.Small cubes with no swim length. The colour fades and the body stays narrow.
- 3.Soft acid water with no KH buffer. The fish hold short term, but condition slides in months.
- 4.A mature filter and room for eight or more fish brings the colour out. Skip nippy or cool-water species. Match to warm, stable hard water at pH 6.5 to 7.5.
About this species
Turquoise rainbowfish are deep-bodied schoolers from Lake Kutubu in Papua New Guinea. Adult males turn a clean blue in a 200L or longer tank with rivals to display to. The colour washes out in cubes and short tanks.
- Boesemani Rainbowfish150L min · same group, similar adult size
- Dwarf Neon Rainbowfish100L min · same fish family
- Celebes Rainbowfish80L min · same fish family
- Threadfin rainbowfish60L min · same fish family
- African freshwater butterflyfishalso intermediate peaceful, similar tank size
- Black ruby barbalso intermediate peaceful, similar tank size
- Boesemani Rainbowfishalso intermediate peaceful, similar tank size
- Bolivian Ramalso intermediate peaceful, similar tank size
- Brown / hockey-stick pencilfishalso intermediate peaceful, similar tank size
- Checkerboard cichlidalso intermediate peaceful, similar tank size
No reverse lookups listed yet.
Plan grid
Key limits are above. Here: pH band, swim level, bioload, and activity.
Swim zones
Care snapshot
Quick compare before you buy. Not a score of how “good” the fish is.
- Beginner ease32
- Peacefulness90
- Community fit79
- Small-tank fit90
- Hardiness54
- Energy86
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Example setups
Starting points only. Run the pair checker for every fish you add.
Rough 200L+ layout: one calm centrepiece, 8–12 small tetras/rasboras, 6–8 corydoras-type bottom fish — verify every name in the pair checker before buying.
Safer directions include: Boesemani Rainbowfish, Dwarf Gourami, Dwarf Neon Rainbowfish.
Prioritise 6+ of Turquoise / Lake Kutubu rainbowfish in 200L+ with filtration sized for messy feeding — add only mates that already pass pair checks with this species.
Compatibility
Tank mates for Turquoise / Lake Kutubu rainbowfish
Usually safer (engine GOOD): Boesemani Rainbowfish, Dwarf Gourami, Dwarf Neon Rainbowfish. Conditional (CAUTION — read the pair page before buying): Angelfish, Corydoras Catfish, German Blue Ram, Neon Tetra, Pea Puffer. Avoid (RISKY): African Cichlid, Green Terror, Oscar. Every name links to a live pair check — the lists are a shortlist, not a stocking plan.
Usually safer
Open a pair page with this fish as the starting point.
Needs planning
Read the blocking rule on each pair page before experimenting.
Usually avoid
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Turquoise / Lake Kutubu rainbowfish + Boesemani Rainbowfish
Behaviour and temperament
Turquoise rainbowfish are peaceful, active midwater schoolers that look boisterous without being fin shredders. Males flash and chase inside a proper group of six or more, and colour holds when the school has real length. They need a swim lane more than a high litre sticker on a tall cube.
What sets them off
- Sudden crowding
- Poor water quality
Fin nipping: Not a habitual fin-nipper; stressed or crowded individuals can still test fins.
Predation: Not a predator toward similarly sized community fish; fry and dwarf shrimp are still fair game for most species.
Territory: Not strongly territorial, but still needs room so its working space does not overlap the next fish.
Planted tanks: excellent — easy plant ideas
In the glass: typical and warning signs
- Males display and chase inside a school of six or more in open midwater.
- Colour deepens with varied food and honest group size, not with a heater alone.
- Dull, hiding fish in a short tank usually need more length and more of their own kind.
- Constant glass pacing means footprint failure before a mystery illness.
- In-school male display is normal sorting, not a reason to break the group up.
- They rarely start fights with robust neighbours; they lose space to nippers instead.
- Add to the school before you add another midwater centrepiece to “calm them.”
- Move them out of any cube that cannot give a real swim lane.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Water, food, and grouping
Hardness
medium
Diet
omnivore
Turquoise rainbowfish take flake and pellets in the midwater rush and colour up harder with frozen foods a few times a week. Males need energy for display; a single dry staple leaves them dull. Feed a pinch the school can reach before surface specialists clear the film.
Shrimp & snails
Cherry shrimp and other dwarfs can coexist with peaceful small fish; baby shrimp are food for almost anything that finds them.
Schooling species — buy 6+ together. Smaller groups stress and lose colour.
- Hold 24 to 28 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 6.5 to 7.5 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Schooling species. Buy 6 or more from the same tank on the same day before adding any centrepiece fish.
- Tank volume meets or exceeds 200L published minimum for adults.
- You can stock at least 6 individuals (group welfare).
- Heater can hold 24–28°C without cooking cooler-water tank mates.
- No known fin-nippers paired with long-finned fish unless you accept documented risk.
Explore and stocking hubs
Tank-mates hub, matching guides, category peers, and litre stocking lists around this species’ minimum tank.
Plan with tools
Check mates as pairs first, then add this fish in the tank builder for the full stocking.
Filtration & heating
A 200L minimum tank needs a filter rated for at least 800L/hr turnover and a heater to hold 24–28°C reliably.
Plant suggestions
Turquoise / Lake Kutubu rainbowfish does well in planted tanks. Plants compatible with 24–28°C and pH 6.5–7.5:
Research: partially verified · Confidence: high · 3 linked source(s). We do not invent citations.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Melanotaenia lacustris
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Melanotaenia lacustris
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Melanotaenia lacustris
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
Common questions about Turquoise / Lake Kutubu rainbowfish
- How big do Turquoise / Lake Kutubu rainbowfish get?
- Turquoise / Lake Kutubu rainbowfish adults run about 10–12 cm. In home tanks they usually land near 12 cm — plan space and filtration for that, not the juvenile in the shop bag.
- What size tank does Turquoise / Lake Kutubu rainbowfish need?
- 200L is the planning floor for adult swimming space and bioload. A 250L+ tank is the more comfortable long-term footprint. Length and depth matter as much as raw litres for active or territorial fish.
- Are Turquoise / Lake Kutubu rainbowfish aggressive?
- Turquoise rainbowfish are peaceful, active midwater schoolers that look boisterous without being fin shredders. Males flash and chase inside a proper group of six or more, and colour holds when the school has real length. They need a swim lane more than a high litre sticker on a tall cube.
- Do Turquoise / Lake Kutubu rainbowfish need to be kept in a group?
- Schooling species — buy 6+ together. Smaller groups stress and lose colour.
- What is the most common mistake with Turquoise / Lake Kutubu rainbowfish?
- Keeping one or two turquoise rainbowfish because the bag looked bright is how keepers invent dull adults. Full colour needs competitive male display in a school of six or more with real length. A pair in a short tank never shows the fish people paid for.
- What fish can live with Turquoise / Lake Kutubu rainbowfish?
- The Turquoise / Lake Kutubu rainbowfish profile lists Boesemani Rainbowfish, Dwarf Gourami, Dwarf Neon Rainbowfish among its safer pairings (engine-checked GOOD). Angelfish, Corydoras Catfish, German Blue Ram, Neon Tetra are conditional (CAUTION): workable only with the specific conditions on each pair page. Avoid African Cichlid, Green Terror, Oscar (RISKY). Run the pair checker for your exact water and tank size before stocking.