MacCulloch's Rainbowfish was scientifically described by O'Gilby in 1915 and its scientific name is Melanotaenia maccullochi. It was first collected from the Barron River in Australia. In 1934, the first specimens where exported to Europe and since this fish readily spawns in aquariums it is now quite common among aquarists.

Description
MacCulloch's Rainbowfish can reach a length of 7 cm (nearly 3 inches). It is on of the smaller species of the genus Melanotaenia. The body of the fish is silvery white (sometimes a yellowish form of white) and decorated with 6-8 reddish-brown stripes that run along the sides. Two distinct colour forms are known, and if you want to keep really colourful Melanotaenia maccullochi you should ideally purchase specimens that hail from Papua New Guinea or the northernmost part of the Cape York Peninsula in Australia. These fishes have a more pronounced tint of yellow on both body and fins, and the dorsal and anal fins are adorned by prominent black striping. If you instead purchase specimens from coastal Queensland, you will most likely get fish that display duller colours and paler striping. In some specimens, the fin stripes are non-existent. The coastal Queensland specimens are however still loved by many aquarists since quite a few specimens compensate for their overall dull appearance by having really red fins that contrasts beautifully against the drab body. Such specimens are often sold under the name Red-finned Rainbowfish. They are not a separate species, only a variant of MacCulloch's Rainbowfish.

Geographical distribution, habitat and conservation

MacCulloch's Rainbowfish Copyright www.jjphoto.dk McCulloch's rainbowfish - Copyright www.jjphoto.dk Melanotaenia maccullochi - Copyright www.jjphoto.dk

MacCulloch's Rainbowfish lives in streams and swamps in a region that stretches from northern Australia to south-western Papua New Guinea. In Papua New Guinea it can be found from Fly River to Bensbach River. You can for instance encounter it in Lake Boset / Lake Herbert Hoover and the Wamriver that drains this lake. The species is believed to exist in Western New Guinea as well, but these rumours have not been proven. In Australia, MacCulloch's Rainbowfish is present in the coastal plains of Queensland, in the McIvor River and in rainforest creeks on the northern bank of the river Daintree. The Australian range stretches northwards all the way to the tip of the Cape York Peninsula.

The typical MacCulloch's Rainbowfish habitat consists of swamps and small creeks, and it can for instance never be found in the main Fly River, only in slow parts of the middle and lower sections. MacCulloch's Rainbowfish is used to clear and acidic water where the pH-value stays in the 5.5-6.5 range.

The populations in New Guinea and the Australian Cape York Peninsula are doing okay, while the populations along the Queensland coast have to deal with more widespread habitat destruction.

Keeping MacCulloch's Rainbowfish in aquariums
MacCulloch's Rainbowfish can be kept in species aquariums or together with other small and non-aggressive fish in a community aquarium. It should not be kept with aggressive species since it will have a hard time fending for itself. It is well liked among hobby aquarists since it can adapt to both alkaline and acidic conditions, but it is best for the fish if you keep the pH-value within the pH 5.5-7.5 interval. The recommended temperature is 23-28 degrees C (73-82 degrees F). Try to resemble the natural habitat of this fish when you set up the aquarium and include both driftwood and aquatic plants. Plenty of hiding spots is important.

Breeding MacCulloch's Rainbowfish
MacCulloch's Rainbowfish will usually reach sexual maturity when its 3-4 centimetres long and can therefore start breeding during the first 6 months of its life if provided with a suitable environment and diet. If you want to breed MacCulloch's Rainbowfish, you need to provide your fish with a suitable spawning medium in the aquarium, e.g. java moss or special spawning mops. During the courting period, the male MacCulloch's Rainbowfish will display a yellow streak on top of his head and back side of the neck. If the water temperature is kept in the upper part of the recommended range, hatching will normally take place within 10 days after spawning. You can feed the fry infusoria and egg yolk until they are big enough to eat newly hatched brine shrimp.

Most breeders move the eggs to a separate container to avoid predation, but it is possible to let the eggs stay in the same aquarium as adult fish provided that the grown ups are really well fed and the aquarium well decorated with plenty of hiding spots for young fry.

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