TankBud

Lake Kutubu rainbowfish

Melanotaenia lacustris

Also known as Turquoise Rainbowfish

FreshwaterFish

Lake Kutubu rainbowfish (Melanotaenia lacustris)
Thomnight (Thomnight) · CC BY-SA 2.0 de

Care at a glance

Temperature
68–77°F
20–25°C
pH
7.0–8.0
Adult size
4.3 in
11 cm
Minimum tank
29 gal
110 L
Temperament
Peaceful
Social behavior
Schooling
Swim level
Middle
Difficulty
Medium
Breeding
Egg depositor · Hard
Rarity
Rare
Family
Melanotaeniidae
Origin
New Guinea

Overview

The Lake Kutubu rainbowfish is a calm midwater schooler, known for the blue and turquoise of its males. It suits a keeper with some experience.

Did you know

The Lake Kutubu rainbowfish can change how blue it looks from moment to moment. Its color brightens or fades with its mood and the light.

Caring for the Lake Kutubu rainbowfish

Keep Lake Kutubu rainbowfish in a group of six or more, in a tank of 29 gal (110 L) or larger. Plant the sides with sturdy plants and keep the center open for swimming. A fine substrate with rockwork and wood suits them.

Keep the water at 68 to 77°F (20 to 25°C) and a pH of 7.0 to 8.0. That range is on the cooler side for a rainbowfish. It should be clean and well oxygenated, with gentle movement. Feed a mix of flake or pellet, frozen bloodworms, daphnia and brine shrimp.

Lake Kutubu rainbowfish are peaceful and pair well with other gentle fish that like the same cool, hard water. Males show the strongest blue. Steady conditions and a mature group bring out the deepest color, so be patient with plainer youngsters.

They spawn continuously, laying small numbers of eggs onto fine plants and mops over weeks. The fry are left to fend for themselves, and breeding them is hard.

Good to know

Melanotaenia lacustris belongs to the rainbowfish family Melanotaeniidae, and its species name means of the lake. It is unusual for a rainbowfish in living naturally in just one lake system. As a fish tied to one highland lake, it is listed as vulnerable in the wild. It also goes by the name turquoise rainbowfish.

In the wild

The Lake Kutubu rainbowfish is endemic to Lake Kutubu and its outflow, in the highlands of Papua New Guinea. The lake is one of the country's largest and clearest. Its water is cool, hard and slightly alkaline.

Weekly picks

Tank mates

The Lake Kutubu rainbowfish is a peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a Lake Kutubu rainbowfish need?

A Lake Kutubu rainbowfish needs at least 29 gal (110 L). It spends most of its time in the middle.

What temperature and pH does a Lake Kutubu rainbowfish need?

A Lake Kutubu rainbowfish is comfortable at 68–77°F (20–25°C) with a pH of 7.0–8.0.

What does a Lake Kutubu rainbowfish eat?

A Lake Kutubu rainbowfish eats a mix of flake or pellet, with frozen bloodworms, daphnia and brine shrimp.

How big does a Lake Kutubu rainbowfish get?

An adult Lake Kutubu rainbowfish reaches about 4.3 in (11 cm).

Does a Lake Kutubu rainbowfish need a group?

Yes. A Lake Kutubu rainbowfish is a schooling species and should be kept in a group, not singly.

How can you tell a male Lake Kutubu rainbowfish from a female?

Males show the strongest blue of the group.

How does a Lake Kutubu rainbowfish breed?

Lake Kutubu rainbowfish spawn continuously, laying small numbers of eggs on fine plants and mops over weeks. The fry are left to fend for themselves, and breeding them is hard.

Related species