All fish / Melanotaeniidae

Lake Kutubu Rainbowfish

Melanotaenia lacustris

Also known as lake kutubu rainbow, kutubu rainbowfish, turquoise rainbowfish, blue rainbowfish, lacustris rainbowfish, lake kutubu rainbow fish, メラノタエニア・ラクストリス, pelangi kutubu, 湖泊彩虹鱼, 库图布湖彩虹鱼

This is a deep-bodied rainbowfish with bright turquoise to electric blue colouring above, a silvery belly and a dark band along the flank, and the males have higher backs. It comes from one clear, hard-water lake in the highlands of Papua New Guinea. People keep it because it is hardy, active and peaceful, and a shoal brings strong colour to a large planted community tank.

Care at a glance

Care level

Easy

Temperament

Peaceful

Adult size

10 cm

Temperature

21 to 26 °C

pH

7 to 8.5

Smallest tank

200 litres

Keep as

Shoal of 6 or more, ideally with more females than males

Diet

Omnivore: quality flakes and pellets, frozen bloodworm, brine shrimp and daphnia, plus some vegetable matter

Swims

Middle of the tank

Lifespan

5 to 8 years

Water

Freshwater

Wild range

Lake Kutubu and the upper Soro River, Kikori basin, Papua New Guinea

Breeding

It scatters eggs over fine-leaved plants or spawning mops over several days, and the eggs hatch in about a week. It breeds readily in captivity. The fry need infusoria or liquid fry food at first and then baby brine shrimp.

Good to know

It is listed as Vulnerable in the wild because its range is so small, so choose captive-bred stock. It needs a long tank with plenty of swimming space, and it can hybridise with other Melanotaenia species if they are kept together.