Product Details

Emerald Green Rainbowfish – Glossolepis wanamensis

Overview:

The Emerald Green Rainbowfish is a rare and elegant rainbowfish from Lake Wanam in Papua New Guinea, with mature males developing a deep body, metallic green to olive sheen and warm golden-orange tones through the flanks and fins. Correctly known as the Lake Wanam Rainbowfish, Glossolepis wanamensis is a peaceful but active shoaling species for a spacious planted aquarium. It is also a conservation-significant fish, so captive-bred, correctly identified stock is especially important.

Key Identification:

Common Name: Emerald Green Rainbowfish
Other Names: Lake Wanam Rainbowfish, Wanam Rainbowfish, Green Wanam Rainbowfish
Scientific Name: Glossolepis wanamensis
Fish Type: Rainbowfish
Water Type: Freshwater

Natural Range & Habitat:

Glossolepis wanamensis is endemic to Lake Wanam, a small lake near Lae in Papua New Guinea. FishBase records it as a high-altitude lake species, found at around 150 m elevation, with aquarium habitat notes including rocks, vegetation and driftwood cover.

Lake Wanam has faced serious ecological pressure from introduced fish. ANGFA reports non-native tilapia, carp and mosquito fish in the lake and notes concern for the future of the endemic Lake Wanam Rainbowfish in the wild. FishBase lists the species as Critically Endangered, so aquarium strains should be maintained responsibly and not hybridised with other rainbowfish.

Appearance & Adult Size:

Emerald Green Rainbowfish have a deep, laterally compressed rainbowfish body, with males becoming fuller-bodied and more colourful as they mature. Adult males can show metallic green, olive, bronze, orange and golden tones depending on lighting, mood, age and strain. Females and young fish are usually slimmer and more subdued, but they are important for natural group behaviour and male display.

Adults usually reach around 8–10 cm, with some references giving males close to 9–10 cm. Large specimens should be treated as mature or near-mature rainbowfish with active swimming needs.

Aquarium Suitability:

This species is best suited to a mature planted community aquarium, species display or conservation-minded rainbowfish setup. It needs clean water, stable conditions and open swimming space through the middle and upper levels. Planting, wood and shaded areas around the sides help the fish feel secure, while the central area should remain open for group movement.

Emerald Green Rainbowfish are peaceful, but they are active feeders, so they are not ideal with very slow, timid or delicate fish that may be outcompeted.

Recommended Aquarium Size:

A practical minimum is 180 litres for a group, with a tank length of at least 100–120 cm recommended. Larger aquariums are preferred for large specimens, stronger male display and mixed rainbowfish communities.

Water Conditions:

Temperature: 24–29°C
pH: 7.0–7.8
Hardness: Moderately hard preferred
Additional Notes: Provide clean, well-filtered water with good oxygenation and regular partial water changes. FishBase gives aquarium conditions around pH 7.8, hardness 15 dH and 29°C, while other aquarium references report Lake Wanam water around pH 7.0–7.8 and approximately 28°C. Avoid soft acidic blackwater conditions and high organic waste.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Emerald Green Rainbowfish are peaceful shoaling fish, but their speed and feeding response can unsettle smaller or slower species. Suitable tank mates include other peaceful rainbowfish, larger tetras, danios, peaceful barbs, robust rasboras, Cory-type catfish suited to the same water, bristlenose plecs, peaceful loaches and calm medium-sized cichlids.

Avoid aggressive cichlids, persistent fin-nippers, very timid fish and slow feeders that may struggle to compete. Keep in a group of at least 6, with 8 or more preferred. Fishkeeper also recommends keeping Lake Wanam Rainbowfish in groups of six or more in a spacious planted aquarium.

Feeding:

Emerald Green Rainbowfish are omnivores and easy to feed once settled. Offer quality flakes, small granules and rainbowfish pellets as the staple diet. Supplement with frozen or live foods such as daphnia, brineshrimp, cyclops, mosquito larvae and bloodworm. Include some vegetable or algae-based foods for balance. Feed measured portions, as rainbowfish are enthusiastic feeders and can outcompete quieter tank mates.

Behaviour in the Aquarium:

This is an active midwater to upper-level fish that spends much of the day moving in a loose group. Mature males may display to females and rival males, showing stronger body colour and raised fins. Seriously Fish describes the species as very peaceful but capable of disturbing smaller or slow-moving fish because of its size and rapid movement. A secure lid is recommended, as active rainbowfish may jump if startled.

Care Notes:

Keep in a mature aquarium with excellent maintenance and low nitrate. Fishkeeper notes that this species is sensitive to organic waste build-up, making efficient filtration and frequent partial water changes important. Do not keep singly or in pairs, and do not mix with other Glossolepis or similar rainbowfish if breeding may occur, as hybridisation can damage conservation value. Source captive-bred fish from reputable lines wherever possible.

Recommended For:

Beginner to intermediate

Availability:

Rare / Specialist rainbowfish / Captive-bred conservation strain when available

Image Disclaimer:

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Natural variation in size, colour, pattern and markings can occur between individual fish.