Melanotaenia maccullochi

Melanotaenia maccullochi [Harvey Creek] - photo© Günther Schmida

Ogilby, 1915
McCulloch's Rainbowfish

Description
Several geographically isolated populations are found in northern Queensland. Male specimens of the variety found between Cairns and Innisfail have deep black irregular horizontal stripes along a silver body. The dorsal and anal fins are orange-red with a lower black margin running along the body line. The caudal fin has a fan of orange-red colouration. Females are much less colourful, though some do show a hint of the male's coloration. Females tend to grow larger and have deeper bodies than males.

The variety found in the drainage division of the Jardine River are characterised by a series of fine black stripes on the sides, with black submarginal bands and white to yellowish margins on the dorsal and anal fins. Females generally have the stripes less defined. They are also a lot smaller than the other varieties, both in length and body depth. The population from the latter area is similar to those that occur in the southwestern lowlands of Papua New Guinea. The varieties found north of Cairns but south of the Jardine River are intermediate. However, the stripe pattern is plain and they do not show the orange-red colouration.

In 1988 a new colour variety was found on a private property known as Pethrick's Forest surrounded by the Litchfield National Park in the Northern Territory. It was collected from a small shallow stream known as Burton Creek. This variety has clear to yellowish dorsal and anal fins with bluish edges above a black sub-marginal band. The body colour is silver to yellowish with a dark mid-lateral stripe and grows to a much smaller size than the other varieties.

Melanotaenia maccullochi is another species that varies across its range, with the Northern Territory population being the most distinctive. Genetic data separate Melanotaenia maccullochi into three groups, Burtons Creek, Etty Bay and Cape York populations. More populations along the eastern drainages need to be examined to determine further genetic variation. The differences between the various populations are considerable and I would not be surprised to see them separated into distinct species at some later date. Therefore, for the serious rainbowfish breeder, it is very important to maintain each distinct population separately in captivity.

Distribution
They are found along the coastal plain between Cairns and Innisfail and from the Daintree River north through Cooktown to the McIvor River. Another area where they are found is Cape York Peninsula, primarily in the Jardine River and its tributaries. They also occur at Cape Flattery and the Olive River and probably occur elsewhere along the east coast of Cape York Peninsula that has suitable habitat. A small isolated population occurs near the Litchfield National Park in the Northern Territory. The known New Guinean distribution encompasses the lower and middle sections of the Fly River westward to the Bensbach River.

Habitat & Ecology
Generally found in clear, moderately flowing streams, grassy wetland swamps and tannic stained ponds in sandy dune country. A temperature range of 22° to 30°C and pH values of 5.5 - 7.5 are found in their natural habitats. Melanotaenia maccullochi may reach a maximum size of 8 cm, but usually less than 5 cm. Spawning occurs from October to December, with females producing between 20-30 eggs each day for several days. Eggs adhere to fine-leaved plants or among the roots of floating vegetation. These hang like Christmas decorations on the plants, each being suspended by a short filament. It will take around 8-9 days at 28° Celsius for the first young to appear. Before spawning, a bright yellow or white stripe is evident in the male. It runs from the tip of the mouth to the first dorsal fin on the dorsal surface of the fish.

Remarks
Initially collected in 1915 from the Barron River, inland from Cairns, north Queensland, and scientifically described by J. D. Ogilby as Melanotaenia maccullochi. They were named after the ichthyologist, Allan R. McCulloch (1885-1925). They were introduced to the International aquarium hobby around 1934, and were one of the most popular aquarium fish from Australia. In the German aquarium magazine "Wochenschrift für Aquarien und Terrarienkunde" in May 1935, Fritz Mayer gave the first account of their breeding, which was translated and elaborated upon by F. H. Stoye in Innes' "The Aquarium" in December 1936.

Contents

Rainbowfishes

Introduction

Scientific Names

Rainbowfish Species