The Lake Kutubu Rainbowfish (Melanotaenia lacustris) is a rare and stunning freshwater fish endemic to Lake Kutubu in Papua New Guinea. Known for its vibrant iridescent scales that shimmer in blue, green, and sometimes yellow hues, it is an active and peaceful schooling fish.
Out of Stock
The Lake Kutubu Rainbowfish (Melanotaenia lacustris) is a rare and stunning freshwater fish endemic to Lake Kutubu in Papua New Guinea. Known for its vibrant iridescent scales that shimmer in blue, green, and sometimes yellow hues, it is an active and peaceful schooling fish.
Iridescent body showing blue to green hues, sometimes with yellow undertones. Laterally compressed, streamlined body with forked tail. Males are more brightly colored and slightly larger; females are paler and smaller. Transparent fins with subtle hints of yellow or orange.
5–8 years with proper care
Omnivorous; feeds on high-quality flakes, pellets, and frozen foods. Supplement with live foods such as brine shrimp, daphnia, and bloodworms. Occasional blanched vegetables like zucchini or spinach support coloration and health.
Lake Kutubu Rainbowfish are ideal for aquarists who want a rare, vibrant, and peaceful schooling species. They thrive in well-maintained tanks with open swimming areas and compatible tankmates.
Intermediate – requires stable water, proper schooling, and high-quality diet.
30+ gallons (for small school)
7.0 to 8.0
8–15 dGH
75–82°F (24–28°C)
3–4 inches
Tetras, rasboras, danios, small peaceful barbs, dwarf gouramis, other rainbowfish. Avoid aggressive or fin-nipping species.
Aggressive or fin-nipping species. Very small or slow-moving fish that may be stressed by active schooling behavior.
Melanotaenia lacustris
Melanotaeniidae
Lake Kutubu, Papua New Guinea – clear, shallow waters with vegetation.
Highly social; best kept in schools of 6 or more. Peaceful and compatible with other mid-level community fish.
Feed 2–3 times daily with flakes, pellets, and frozen/live foods. Occasionally supplement with blanched vegetables for optimal health and vibrant coloration.
Egg-scatterer; deposits eggs among fine-leaved plants or spawning mops. Adults do not guard eggs. Condition male and female with protein-rich foods before spawning. Fry feed on infusoria or newly hatched brine shrimp.
pH: 7.0–8.0, Temperature: 75–82°F (24–28°C), Hardness: 8–15 dGH, Ammonia/Nitrite: 0 ppm, Nitrate: <20 ppm
Sensitive to poor water quality; prone to stress, ich, and bacterial infections. Maintain clean water, regular changes, and balanced nutrition.
Peaceful, schooling, and active swimmer. Best kept in groups of 6 or more to display natural behavior and vibrant colors. Compatible with other peaceful mid-level community fish.
Native exclusively to Lake Kutubu in Papua New Guinea, this Rainbowfish inhabits clear, shallow waters with abundant vegetation. Adults reach 3–4 inches and require a minimum tank size of 30+ gallons for a small school. Open swimming space with moderate planting and stable water parameters is essential for optimal health and color expression. Lake Kutubu Rainbowfish are perfect for aquarists seeking a peaceful, colorful, and schooling centerpiece fish.