Turquoise rainbowfish care guide
Also called: Lake Kutubu rainbowfish, Kutubu rainbowfish, Turquoise rainbow
The turquoise rainbowfish, also called the Lake Kutubu rainbowfish, is a hardy, peaceful schooler whose males glow metallic blue-green. Keep six or more in a 4 ft (120 cm) tank with hard, alkaline, slightly cooler tropical water.
Turquoise rainbowfish need a tank of at least 29 gallons (110 L), a group of 6 or more, and water at 22–25°C (72–77°F) with a pH of 7–8. They grow to about 11 cm (4.3 in) and are peaceful.
Plan a tank with turquoise rainbowfishSee all tank mates
Turquoise rainbowfish quick facts
| Scientific name | Melanotaenia lacustris |
|---|---|
| Family | Melanotaeniidae |
| Origin | Lake Kutubu and the Soro River, Southern Highlands, Papua New Guinea (endangered in the wild; aquarium fish are captive-bred) |
| Adult size | 11 cm (4.3 in) |
| Minimum tank | 29 gallons (110 L), at least 120 cm (47 in) long |
| Temperature | 22–25°C (72–77°F) |
| pH | 7–8 |
| Hardness (GH) | 10–20 dGH |
| Group size | 6 or more (shoaling fish) |
| Temperament | Peaceful |
| Swims at | Middle |
| Diet | Omnivore |
| Care level | Easy |
| Lifespan | 5–8 years |
| Safe with shrimp? | No, eats shrimp |
| Safe with plants? | Yes |
- Known jumper: keep a tight-fitting lid.
Tank setup
A group of six needs at least 29 gallons (110 L) in a tank 4 ft (120 cm) long. Plant the back and sides, add some rocks and driftwood, and keep a wide open lane for swimming. A tight lid is a good idea, as rainbowfish can leap when frightened.
How many turquoise rainbowfish in a tank?
The smallest common tank that suits turquoise rainbowfish is a 55 gallon. Here is roughly how many fit in each size when they are the only fish, based on adult size and waste output. Leave room if you want tank mates.
| Tank | Turquoise rainbowfish (alone) |
|---|---|
| 3 gallon | Too small |
| 5 gallon | Too small |
| 10 gallon | Too small |
| 15 gallon | Too small |
| 20 gallon | Too small |
| 20 gallon long | Too small |
| 29 gallon | Too small |
| 40 gallon | Too small |
| 55 gallon | 6–13 |
| 75 gallon | 6–18 |
| 125 gallon | 6–31 |
What you need for turquoise rainbowfish
Sized for a 29 gallon tank, the smallest common size that suits a group of 6 turquoise rainbowfish. For a different tank or a mix of fish, use the stocking calculator for a list sized to your plan.
Tank and equipment
- 29 gallon aquarium (tank or kit) (opens Amazon in a new tab)Bigger tanks are more stable and easier for beginners. How to choose
- Aquarium stand for 29 gallons (opens Amazon in a new tab)The water alone weighs about 242 lb (110 kg), before glass, gravel and rock. How to choose
- Adjustable heater, 75 W (opens Amazon in a new tab)Holds about 74 °F (23.5 °C) in a room at 65 °F (18 °C). How to choose
- Aquarium thermometer (opens Amazon in a new tab)Check it daily: heaters can fail stuck on or off. How to choose
- Hang-on-back filter rated 115–175 GPH (opens Amazon in a new tab)Community tank: 4–6 times the tank volume per hour. How to choose
- About 45 lb of aquarium gravel (opens Amazon in a new tab)Enough for a layer about 2 in (5 cm) deep. Smooth gravel suits most community fish. How to choose
- Water conditioner (dechlorinator) (opens Amazon in a new tab)Removes chlorine and chloramine from tap water. Seachem Prime is a popular, concentrated choice. How to choose
- Liquid test kit (ammonia, nitrite, nitrate, pH) (opens Amazon in a new tab)Liquid kits are more accurate than strips. The API Freshwater Master Test Kit is the common choice. How to choose
- Gravel vacuum (siphon) (opens Amazon in a new tab)Cleans the gravel and does the water change in one go. How to choose
- LED aquarium light, about 30 in long (opens Amazon in a new tab)Match the light to the tank length. Basic LEDs grow easy plants. How to choose
Food and extras for turquoise rainbowfish
- Tropical fish pellets (opens Amazon in a new tab)A good staple for medium community fish.
- Tight-fitting lid for a 29 gallon tank (opens Amazon in a new tab)Turquoise rainbowfish can jump out of an open tank.
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Water parameters
Keep it a little cooler than many tropical fish, at 22–25 °C (72–77 °F), with pH 7.0–8.0 and 10–20 dGH. It will not thrive in soft, acidic water. Good filtration and weekly water changes keep the color bright.
Best tank mates for turquoise rainbowfish
These popular species share turquoise rainbowfish' water needs and temperament. See the full list of 76 good matches.
Nerite snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Guppy
5 cm (2 in) · 22–27°C (72–81°F)
Neon tetra
3.5 cm (1.4 in) · 21–25°C (70–77°F)
Panda corydoras
4.5 cm (1.8 in) · 21–25°C (70–77°F)
Bristlenose pleco
12 cm (4.7 in) · 22–26°C (72–79°F)
Bronze corydoras
7 cm (2.8 in) · 21–26°C (70–79°F)
Zebra danio
5 cm (2 in) · 18–25°C (64–77°F)
Tiger barb
7 cm (2.8 in) · 22–27°C (72–81°F)
Avoid keeping turquoise rainbowfish with
- Cherry shrimp: Turquoise rainbowfish eats small shrimp like cherry shrimp.
- Boesemani rainbowfish: They need different temperatures: Turquoise rainbowfish 22–25°C (72–77°F), boesemani rainbowfish 26–29°C (79–84°F).
- Chinese algae eater: Chinese algae eater is aggressive and will bully or injure peaceful turquoise rainbowfish.
- Convict cichlid: Convict cichlid is aggressive and will bully or injure peaceful turquoise rainbowfish.
- Discus: They need different temperatures: Turquoise rainbowfish 22–25°C (72–77°F), discus 28–30°C (82–86°F).
- Electric yellow cichlid: Electric yellow cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Turquoise rainbowfish don't belong in that setup.
Feeding
It is an omnivore that takes almost any food. Use a quality flake or small pellet as the staple and add frozen or live bloodworms, brine shrimp and daphnia a few times a week. Some spirulina or other plant-based food rounds out the diet.
Behavior
It is peaceful but fast and active, so slow or timid fish can feel stressed. Good tank mates are similar-sized rainbowfish, barbs, danios, larger tetras and corydoras that like the same cooler, harder water. Males display to each other with fins spread but seldom do damage. Adults will eat small shrimp.
Breeding
Mature males are larger, deeper-bodied and brighter, with an orange patch above the gill cover; ripe females look plumper. Pairs scatter eggs over fine-leaved plants or a spawning mop over several days. Eggs hatch in about 7–12 days. Fry need infusoria first, then baby brine shrimp after about a week.
Tips from experienced keepers
- Color shifts with mood and light. A calm, well-fed group shows the strongest turquoise.
- Match it with fish that are happy at 22–25 °C (72–77 °F) rather than very warm-water species.
- Keep more females than males to spread out the males' displays.
- Wild fish come from a single lake system and are threatened, so buy captive-bred stock.
Frequently asked questions
Are turquoise rainbowfish and Lake Kutubu rainbowfish the same fish?
Yes. Both names refer to Melanotaenia lacustris, which lives only in Lake Kutubu and its outlet river in Papua New Guinea.
How big do turquoise rainbowfish get?
Adults usually reach about 4–4.5 in (10–12 cm). Males grow larger and deeper-bodied than females.
How many turquoise rainbowfish should I keep?
Keep at least six, and more if your tank allows. Groups with several females look and behave best.
Sources
We checked these references when writing this page. Values are for healthy long-term keeping, not survival limits. Last reviewed 2026-10-13. See our editorial policy.