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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
Hard
Rarity
Rare
Family
Melanotaeniidae
Origin
New Guinea

Overview

Lake Kutubu rainbowfish are calm, midwater schoolers best kept in a group of six or more, where males glow in the blue and turquoise the species is known for. They are peaceful and pair well with other gentle fish that enjoy the same cool, hard water. Steady conditions and a mature group bring out the deepest color, so be patient with plainer youngsters. Feed a mix of flake or pellet, frozen bloodworms, daphnia, and brine shrimp. Plant the sides and keep the center open for swimming. Aim for a tank around 110 liters or larger.

In the wild

This species is endemic to Lake Kutubu and its outflow in the highlands of Papua New Guinea, one of the country's largest and clearest lakes. The water is cool, hard, and slightly alkaline, which suits a pH of about 7 to 8 and a temperature between 20 and 25 degrees Celsius, on the cooler side for a rainbowfish. Recreate it with fine substrate, rockwork and wood, sturdy plants around the edges, and clean, well-oxygenated water with gentle movement.

Good to know

Melanotaenia lacustris belongs to Melanotaeniidae and grows to around 11 centimeters. The name lacustris means of the lake, and the species is unusual for a rainbowfish in living naturally in just one lake system. Males show the strongest blue, shifting shade with mood and light. It is a continuous egg-scatterer, laying small numbers of eggs onto fine plants and mops over weeks, with the fry left to fend for themselves, so breeding is rated hard.

Did you know

The Lake Kutubu rainbowfish can change how blue it looks from moment to moment, brightening or fading with its mood and the light. As a fish tied to one highland lake, it is listed as vulnerable in the wild.

Weekly picks

Tank mates

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.

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.

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