Turquoise Rainbowfish
Melanotaenia lacustris
Also known as: Lake Kutubu rainbowfish, Turquoise rainbow
Quick Facts
- Adult size: 10-12 cm (4-4.75 inches)
- Minimum tank size: 150 litres (40 gallons)
- Lifespan: 5–8 years
- Temperament: peaceful
- Swimming level: top-and-middle
- Diet: omnivore
- Minimum group size: 6
- Difficulty: intermediate
Water Parameters
- Temperature: 20–25°C
- pH: 7–8
- Hardness (GH): 179–357 ppm (10–20 dGH)
Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.
Care Summary
A shimmering, pastel blue-green rainbowfish from Lake Kutubu in the highlands of Papua New Guinea, the turquoise rainbow is one of the most striking of the blue rainbows, its colour deepening with age and best seen in a mature male within a group. Reaching around 10 to 12cm, it is an active, peaceful schooling fish that needs a group of at least six, a tank with real swimming length, and hard, alkaline water: unlike many tropical fish it dislikes soft, acidic conditions, which conveniently suits the hard tap water common across much of Australia. It takes a little time to colour up and settle, rewarding patience with a glowing display. Buy tank-bred stock, as the wild lake population is threatened by habitat change and over-collection. A superb, hardy centrepiece schooler for a hard-water community.
Tankmates
A peaceful, active schooler for a hard-water community, best in a group of six or more with other rainbowfish, denison barbs, larger barbs, bristlenose, and corydoras. It wants hard, alkaline water and real swimming length, and its size and pace can overwhelm very small or timid nano fish, so pair it with similarly robust company. Avoid soft, acidic setups, bettas, and dedicated fin-nippers. Buy tank-bred fish to spare the threatened wild population.
Compatible with
- Boeseman's Rainbowfish
- Red Rainbowfish
- Murray River Rainbowfish
- Denison Barb
- Bristlenose Pleco
- Bronze Corydoras
- Gold Barb
Avoid keeping with
- Betta
- Chili Rasbora
- Fin Nippers
- Large Cichlids
Common Problems
- poor colour and health in soft, acidic water
- needing swimming length that small tanks cannot provide
- being slow to colour up, so often passed over as a drab juvenile
- sourcing wild-caught stock from a threatened lake rather than tank-bred fish
Sources: seriouslyfish.com, fishbase.org, angfa.org.au · Last updated: 2026-10-13