McCulloch's Rainbowfish

About

The smallest Melanotaenia in this catalogue, and the odd one out. McCulloch's rainbowfish tops out at 7 cm and usually sells at half that, with a bronze-to-brown body carrying a series of dark lateral stripes and orange to rich red fins in nuptial males — stripes and red rather than the two-tone body of the Boesemani rainbowfish or the turquoise of the Lake Kutubu rainbowfish, although an unusual blue variant is known from the Hope Vale region. It is also the only Melanotaenia in this catalogue genuinely at home in soft, acidic water — the threadfin rainbowfish manages it too, but from a different genus: the trade range runs pH 5.5-8.0 depending on collection locality, and the wild habitat is tannin-stained lowland swamp and Pandanus creek at pH 5.5-7. That makes it the rainbowfish you can put in a blackwater community, where the Lake Tebera or Boesemani fish would slowly fail. The catch is that the trade sells several geographically isolated forms — Jardine River, Burton Creek, Hope Vale, Etty Bay and others — which differ in stripe pattern, fin colour and size and will hybridise if mixed, so buy one form and keep it pure. Females tend to grow slightly larger and deeper than males.

Care

A shoal of six or more in a 60 cm tank of 55-60 L, heavily planted with open lanes and slow flow. Almost anything from pH 5.5 to 8 and 20-30 °C works, which is a wider range than any other Melanotaenia in this catalogue tolerates — but keep only one locality form per tank, because the variants interbreed and the offspring are worth nothing to anyone. Lid on; it jumps like every rainbowfish.

Diet

Unfussy omnivore taking dried, frozen and live foods. Small items only, fed at or near the surface: daphnia, cyclops, brine shrimp nauplii and micro pellets, with live or frozen food two or three times a week to bring the red up in the fins.

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 McCulloch's Rainbowfish need?

A McCulloch's Rainbowfish needs an aquarium of at least 60 litres (15.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a McCulloch's Rainbowfish need?

McCulloch's Rainbowfish does best at 20–30 °C (68–86 °F), pH 5.5–8 and a general hardness of 3–15 °dGH.

What group size does a McCulloch's Rainbowfish need?

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

Is the McCulloch's Rainbowfish suitable for beginners?

Yes — McCulloch's Rainbowfish is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Sources

• Seriously Fish — Melanotaenia maccullochi (Dwarf Rainbowfish)
• FishBase — Melanotaenia maccullochi, Macculloch's rainbowfish
• AquaInfo — Melanotaenia maccullochi, McCulloch's Regenboogvis (text by Adrian R. Tappin, Home of the Rainbowfish)
• Aquarium Co-Op — Top 10 Amazing Rainbowfish for Your Next Freshwater Aquarium