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| Melanotaenia duboulayi [Kangaroo Creek] - photo© Günther Schmida |
(Castelnau, 1878)
Crimsonspotted Rainbowfish
Description
First described as Atherinichthys duboulayi by Castelnau in 1878. Later known as Nematocentris fluviatilis and Melanotaenia fluviatilis. Following a review of the rainbowfish group by Allen in 1980, they were reclassified as Melanotaenia splendida fluviatilis. Their current scientific name follows from a study of its early life-history stages by Crowley, et al., in 1986. This study resulted in Melanotaenia splendida fluviatilis being separated into two species, Melanotaenia duboulayi from the eastern coastal drainage systems of northern New South Wales and southern Queensland, and Melanotaenia fluviatilis from the inland Murray-Darling River system.
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| Melanotaenia duboulayi [Kin Kin Creek] - photo© Günther Schmida |
Melanotaenia duboulayi exhibit considerable colour variations over their wide geographical range. Generally, the body is silvery-blue or green ranging through deep bluish or yellow tones. The scale rows are marked with narrow yellow lines and overlaid with orange to brilliant red. A prominent spot of crimson red is seen on the operculum, the fin colours are variable from clear, yellowish to red, with red flecks and dark margins. These dark margins become intensely black in males during spawning display. Males are easily distinguished from females by their brighter colours and the dorsal fins are extended and usually overlap. Females have rounded dorsal and anal fins, which are smaller and lack the dark edges. Males are also larger than females.
Not easily distinguished from Melanotaenia fluviatilis. Principal variations are body depth, fin counts, and colour pattern. In addition, there are clear differences in egg characteristics and larval development. Melanotaenia fluviatilis often have a broader head and blunter snout compared to Melanotaenia duboulayi.
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| Melanotaenia duboulayi [Gin Gin Creek] - photo© Günther Schmida |
Distribution
Initially collected in the 1870's from the Richmond River in New South Wales by a man named Duboulay. The distribution includes the narrow coastal strip, east of the Great Dividing Range, from the Hastings River, near Port Macquarie in New South Wales to Bundaberg in Queensland.
Habitat & Ecology
Melanotaenia duboulayi is a subtropical species found in relatively still, clear water, in water temperatures between 18-28° Celsius. Habitat includes freshwater rivers, streams, billabongs, reservoirs, swamps, and ponds with dense aquatic vegetation. Their natural environment is subjected to seasonal variations with water temperature, pH (5-8), and hardness levels varying considerably. They are usually found around sub-surface vegetation, submerged logs, or branches.
Body slender and compressed but depth increasing with age. Two dorsal fins, very close together, the first much smaller than the second. May reach a maximum size of 12 cm SL, but usually less than 10 cm. Spawning occurs from September to December before the onset of summer rains. Juvenile fish grow quickly and reach maturity in the year following hatching. Females produce between 100 and 200 eggs, spawning a number of times daily for several days. Eggs adhere to water plants and hatching occurs after 6-7 days.
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| Melanotaenia duboulayi [Burnett River] - photo© Neil Armstrong |
Remarks
Melanotaenia duboulayi is the original "Australian Rainbowfish" and were being maintained in the aquarium hobby around the turn of the century. In 1927, a number of rainbowfishes were send from Australia to Germany. It is believed that from this initial shipment representatives were introduced to the organised aquarium hobby throughout Europe, and then to North America. In 1930 a number of Melanotaenia duboulayi were collected in the Mississippi River. This was one of the earliest accounts of an introduced ornamental fish found in the USA.
Melanotaenia duboulayi were commonly known as the Crimson-Spotted Sunfish and mistakenly identified as Melanotaenia nigrans. They are probably the species upon which today's common name "Rainbowfish" is based.
© Copyright Adrian R. Tappin
Updated January, 2007.
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