Allen's Rainbowfish

About

Not a Melanotaenia, and that is the first thing worth knowing about it. Chilatherina is a separate rainbowfish genus of some eleven species, endemic to New Guinea and nowhere else, split from Melanotaenia chiefly on jaw structure — nothing you can see across a shop tank. Some Chilatherina also change colour markedly with age, so an old fish and a young one can look like different species; in every other respect they are kept and bred exactly like a Melanotaenia. Allen's rainbowfish is brownish over the front of the body, shading to turquoise behind, with each scale row separated by a narrow brown or dull orange line, a dark blue mid-lateral band about two scale rows deep running from behind the eye to the tail base, punched with about five white notches just behind the pectoral, and an intense white stripe with a dull orange lower edge below it. Second dorsal and anal fins are translucent blue going red at the edges, and on a male they run slightly long and pointed; on a female they are blunt and carry no red at all. Almost everything in the trade is the "Wapoga" form, traced to a 2008 collection on the Wapoga River, and unusually for a rainbowfish it already looks good half-grown, at 4-5 cm. Adults reach about 9 cm and are usually under 7. The IUCN assessed the species Vulnerable in December 2019.

Care

Six or more in a planted tank of at least 100 cm and 120 L, with clean, well-oxygenated water at 24-28 °C, neutral to slightly alkaline pH and moderate flow — the type locality is a cold, clear, fast mountain stream over gravel. Peaceful and undemanding beyond that, but active, so leave open swimming lanes and keep a tight lid. Vendor listings that claim 10-12 cm are inflated: the described species and both specialist accounts stop at about 9 cm.

Diet

Omnivore. Wild food items include filamentous algae, small crustacea, ants and beetles blown onto the surface, and aquatic insect larvae. Flake and small pellets daily, live or frozen brine shrimp, daphnia and bloodworm several times a week, and a green component in the rotation.

Telling males from females

What works for this species, most reliable first.

• Colour and patternStrong · from about 6 months, and only on a settled fish

  In rainbowfish, killifish and several barbs the male carries the colour — deeper and more saturated, intensifying further when he displays.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

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Frequently asked questions

What tank size does a Allen's Rainbowfish need?

A Allen's Rainbowfish needs an aquarium of at least 120 litres (31.7 US gallons) with a footprint at least 100 cm (39.4 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Allen's Rainbowfish need?

Allen's Rainbowfish does best at 22–30 °C (71.6–86 °F), pH 6.8–8 and a general hardness of 5–20 °dGH.

What group size does a Allen's Rainbowfish need?

Allen's Rainbowfish is a social species — keep a group of at least 6 so natural behaviour emerges and stress stays low.

Is the Allen's Rainbowfish suitable for beginners?

Allen's Rainbowfish sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.

Sources

• FishBase — Chilatherina alleni
• Aquarium Glaser — Chilatherina alleni (fish archive, 18 December 2024)
• AquaInfo — Chilatherina alleni, Allen's Regenboogvis (text by Adrian R. Tappin, Home of the Rainbowfish)
• Aquadiction — Wapoga Rainbowfish, Chilatherina alleni
• Aquarium Co-Op — Top 10 Amazing Rainbowfish for Your Next Freshwater Aquarium