Product Details

Pagwi Rainbowfish – Melanotaenia affinis “Pagwi”

Overview:

The Pagwi Rainbowfish is a colourful locality form of Melanotaenia affinis, a New Guinea rainbowfish valued for its active schooling behaviour, metallic body sheen and striking mature male display. Young or small specimens may look modest at first, but well-kept adults can develop impressive colour, especially when maintained in a mixed-sex group with clean water and plenty of swimming space. This is a peaceful but energetic community fish for a spacious tropical aquarium, not a small nano species.

Key Identification:

Common Name: Pagwi Rainbowfish
Other Names: Pagwi New Guinea Rainbowfish, North New Guinea Rainbowfish, New Guinea Rainbowfish, Red-finned Rainbowfish, Melanotaenia affinis “Pagwi”
Scientific Name: Melanotaenia affinis
Fish Type: Rainbowfish
Water Type: Freshwater

Natural Range & Habitat:

The Pagwi form is a locality strain of Melanotaenia affinis, a species native to New Guinea. The “Pagwi” name is associated in the hobby with the Sepik River area of Papua New Guinea, while the wider species is recorded from northern New Guinea drainages. FishBase lists Melanotaenia affinis as a freshwater, benthopelagic tropical species from New Guinea, while Australian import-risk documentation notes that the species is frequently found in rainforest streams, around submerged vegetation, logs and branches, and also in lakes, swamps and lagoons.

In the aquarium, it is best provided with clean, oxygen-rich water, planted cover around the edges and open midwater swimming space.

Appearance & Adult Size:

Small Pagwi Rainbowfish are usually slimmer and less colourful than mature adults, but males improve greatly with age, condition and social display. Adult males can show metallic body colour, warm red or orange fin tones and a distinctive bright display stripe when courting. Specialist rainbowfish references note that the Pagwi form shows its condition clearly through colour, and males may develop a pale display stripe from the snout towards the dorsal area during courtship.

Adults can reach around 10–12 cm, with FishBase listing Melanotaenia affinis at up to 11.5 cm standard length for males and 10 cm standard length for females.

Aquarium Suitability:

This is a strong choice for a larger planted community aquarium, mixed rainbowfish display or New Guinea-style setup. Pagwi Rainbowfish are active midwater swimmers, so they need length and open space rather than a cramped, heavily cluttered tank. They suit aquariums with hardy plants, wood, rounded stones and areas of moderate flow, provided there is still clear room for the group to move.

They are not suitable for nano aquariums, very shy tank mates or slow fish that may be unsettled by fast feeding activity.

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 preferable for adult groups, mixed rainbowfish communities or stronger male display behaviour.

Water Conditions:

Temperature: 22–28°C
pH: 6.5–8.0
Hardness: Moderately hard preferred; adaptable if stable
Additional Notes: FishBase gives a broad temperature range of 20–30°C, while Seriously Fish lists 20–30°C, pH 6.5–8.0 and hardness 8–20°H for Melanotaenia affinis. For best long-term care, provide stable, well-filtered water, good oxygenation and regular water changes. Avoid very soft, unstable water and avoid poor maintenance, as rainbowfish show their best colour in clean conditions.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Pagwi Rainbowfish are peaceful, active shoaling fish. Suitable tank mates include other peaceful rainbowfish, larger tetras, rasboras, danios, peaceful barbs, Cory-type catfish, bristlenose plecs, small to medium peaceful cichlids and other robust community fish that enjoy similar water conditions.

Avoid aggressive cichlids, fin-nippers, tiny fish that may be intimidated, and very slow or delicate species that cannot compete at feeding time. Keep in a group of at least 6, with 8 or more preferred. A mixed-sex group is ideal, as males usually colour up best when displaying to females and rival males.

Feeding:

Pagwi Rainbowfish are omnivores and usually feed readily. Offer quality flakes, small granules and rainbowfish pellets as the staple diet, supported with frozen or live foods such as daphnia, brineshrimp, cyclops, bloodworm and mosquito larvae. Specialist rainbowfish information notes that M. affinis feeds on a range of small invertebrates, including crustaceans and insect larvae, so varied small foods are ideal. Include some vegetable or algae-based foods for balance.

Behaviour in the Aquarium:

This species spends most of its time in the middle and upper levels, moving in a loose group and becoming especially active at feeding time. Mature males may display to each other with intensified body colour, raised fins and a bright courtship stripe. They are peaceful rather than aggressive, but their constant movement means they are best kept with confident community fish. A secure lid is recommended, as rainbowfish can jump when startled.

Care Notes:

Buy small specimens with their adult size in mind. Pagwi Rainbowfish need a group, a long aquarium and consistent water quality. Do not keep singly or in pairs, as small numbers can become nervous and less colourful. Maintain regular partial water changes, provide open swimming space and avoid overcrowding. Young fish often take time to develop their strongest colour, so patience, good diet and a balanced group are important.

Recommended For:

Beginner to intermediate

Availability:

Occasional / Specialist rainbowfish strain / Captive-bred 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.