Lake Kutubu Rainbowfish (Melanotaenia lacustris)

The Lake Kutubu Rainbowfish (Melanotaenia lacustris) is a beautiful and peaceful freshwater fish native to Lake Kutubu in Papua New Guinea. Known for its shimmering blue-green body, subtle yellow coloration, and attractive fins, this active schooling fish is a popular choice for planted aquariums and peaceful community tanks.

Active, peaceful, and relatively easy to care for, the Lake Kutubu Rainbowfish looks especially attractive when kept in a proper group. Its metallic coloration can become more vibrant with good water quality, a varied diet, and suitable aquarium lighting, making it an excellent addition to natural-looking community aquariums.

What We Like About This Fish

• Beautiful metallic blue-green coloration
• Attractive yellow and orange fin accents
• Peaceful and active community fish
• Excellent schooling behavior
• Ideal for planted and natural-style aquariums
• Relatively easy to care for
• Looks best when kept in a proper group

Recommended Tank Parameters

• Tank Size: Minimum 120 liters (30 gallons)
• Temperature: 22–28°C (72–82°F)
• pH: 7.0–8.0
• Water Hardness: Soft to moderately hard
• Water Flow: Gentle to moderate

A well-planted aquarium with driftwood, open swimming space, and areas of dense vegetation provides an ideal environment for Lake Kutubu Rainbowfish. A longer aquarium with plenty of swimming room is recommended because these fish are active swimmers.

Care Guidelines

Diet: Omnivorous. Feed a varied diet of high-quality flakes and small pellets supplemented with frozen or live foods such as bloodworms, daphnia, and brine shrimp. Small, regular meals help maintain good health, growth, and coloration.

Social Behavior: Peaceful and social. Lake Kutubu Rainbowfish should be kept in groups of at least 6, with larger groups providing more natural schooling behavior and increased confidence. They are suitable for peaceful community aquariums with similarly sized and active tank mates.

Origin

Oceania – Lake Kutubu, Papua New Guinea

Average Adult Size

Approximately 10–12 cm (4–4.7 inches)

Average Purchase Size

Approximately 4–6 cm (1.5–2.4 inches)

Schooling Fish

Yes. Lake Kutubu Rainbowfish are social schooling fish and should ideally be kept in groups of 6 or more.

Shrimp Safe

Mostly yes with adult shrimp. They may coexist with larger adult shrimp, but their size and active feeding behavior mean that newly hatched shrimp and very small shrimplets may be eaten.

The Lake Kutubu Rainbowfish is an excellent choice for aquarists looking for a peaceful, colorful, and active schooling fish. With a suitable group, spacious aquarium, good water quality, and a varied diet, these attractive rainbowfish can become a beautiful addition to a planted community aquarium.