A stunning, deep-bodied rainbowfish endemic to Lake Kutubu in Papua New Guinea. Famous for their ability to shift colors from deep teal to bright iridescent blue depending on mood and water quality. They are active schooling fish that thrive in hard, alkaline water.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard / Mixed Sex
Commonly sold as juveniles (4-6cm). Coloration may be muted silver/grey until maturity. Must be kept in schools of 6+ to reduce stress.
Differs in 2 traits from base species
Also known as: Juvenile
Male
Mature males develop a very deep chest (nuchal hump) and intense turquoise coloration. They display frequently to females and rival males.
Differs in 3 traits from base species
Also known as: Show Male
Female
More slender and often slightly smaller than males. Color is a more muted bluish-silver. Essential in the school to encourage male coloration.
Differs in 1 trait from base species
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🟢Ideal Tank MatesTurquoise Rainbowfish Care Guide Summary
The Turquoise Rainbowfish, scientifically known as Melanotaenia lacustris, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 12 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 Turquoise Rainbowfish requires a freshwater only aquarium with a minimum volume of 160 litres and a tank length of at least 120 cm. Water temperature should be maintained between 20°C and 25°C, with a pH range of 7–9 and a general hardness of 10–25 dGH. A moderate water flow is preferred. An aquarium test kit can help you monitor these values.
The Turquoise Rainbowfish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 3 varieties: Standard / Mixed Sex, Male, and Female. 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.
Turquoise Rainbowfish Habitat Setup
When setting up an aquarium for the Turquoise 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 and dense planting to provide cover, break sightlines, and reduce stress. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Turquoise Rainbowfish Compatibility Notes
Classified as peaceful, the Turquoise 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.
Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Turquoise Rainbowfish.
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
125 Gallon Standard
150 Gallon High
Frequently Asked Questions About Turquoise Rainbowfish
How big does Turquoise Rainbowfish get?
Turquoise Rainbowfish (Melanotaenia lacustris) typically reaches a maximum adult size of approximately 12 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Turquoise Rainbowfish need?
A minimum aquarium volume of 160 litres and a tank length of at least 120 cm are recommended for Turquoise Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Turquoise Rainbowfish need?
Turquoise Rainbowfish thrives in freshwater only conditions with a temperature range of 20–25°C, a pH between 7 and 9, and a general hardness of 10–25 dGH. A moderate water flow is preferred.
Is Turquoise Rainbowfish peaceful or aggressive?
Turquoise 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 Turquoise Rainbowfish should be kept together?
Turquoise 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 Turquoise Rainbowfish have any special tank requirements?
Yes. Turquoise Rainbowfish benefits from plants - densely covered and plants - lighly covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Turquoise Rainbowfish need a lid on the tank?
Yes. Turquoise 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.
Similar Species
Boeseman's Rainbowfish
Melanotaenia boesemani
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.
Red Rainbowfish
Glossolepis incisus
Native to Lake Sentani in Indonesia, this species is famous for the brilliant salmon-red coloration of mature males. They are large, active schooling fish that develop a distinct high-arched back as they age. Females are vastly different in appearance (olive-gold). They require hard, alkaline water and plenty of swimming space.
Celebes Rainbowfish
Marosatherina ladigesi
An active, schooling fish native to the karst (limestone) streams of Sulawesi, Indonesia. Known for their striking neon blue lateral stripes and yellowish fins. They strictly require hard, alkaline water to thrive and are highly sensitive to soft, acidic conditions. A peaceful species that requires plenty of open swimming space.
Threadfin Rainbowfish
Iriatherina werneri
A delicate and exquisitely shaped nano rainbowfish native to New Guinea and Northern Australia. They are famous for the males' long, filamentous fins and butterfly-like display behavior. Due to their incredibly small throats, they require micro-foods. They are shoaling fish that are easily intimidated by boisterous tank mates.
Forktail Blue-eye
Pseudomugil furcatus
A highly active, nano shoaling fish native to Papua New Guinea. Recognized by their striking blue eyes and energetic swimming patterns. They are peaceful but require open horizontal swimming space and the company of their own kind to thrive. Due to their short lifespan (2-3 years), they mature quickly and display near-constant courtship behavior.
Rainbow Shark
Epalzeorhynchos frenatum
A popular, active freshwater 'shark' (actually a cyprinid) known for its striking red fins contrasting with a dark or albino body. They are highly territorial bottom-dwellers. Only keep one per tank, as they are notoriously aggressive toward their own kind, other 'sharks' (like the Red Tail Shark), and similar-looking bottom feeders.