Ornate Rainbowfish, Rhadinocentrus ornatus Regan 1914

Other Names: Blue Spotted Sunfish, Moreton Island Sunfish, Neon Light Sunfish, Ornate Rainbow Fish, Porthole Fish, Soft-spined Rainbowfish, Soft-spined Sunfish, Southern Soft-Spined Rainbowfish, Southern Soft-spined Sunfish, Southern Soft-spined Sun-fish, Southern Sunfish

Summary:

A small slender somewhat elongate rainbowfish with dark scales margins creating a striking network pattern. Body semi-transparent with two rows of scales with black margins along mid-sides; red or pale metallic blue iridescent scales immediately below the dorsal-fin base; a black stripe along the anal-fin base; dorsal, anal and caudal fins usually blue (sometimes red) with black margins.

Ornate Rainbowfish vary in colour throughout their distribution. Most have body scales with black margins forming a network pattern, and individuals from very dark tannin-stained waters may be almost black.

Underwater footage of Ornate Rainbowfish in the Searys Creek, QLD.

Video of Ornate Rainbowfish from Searys Creek, Queensland.

Ornate Rainbowfish from Teewah Creek Tin Can Bay.

Cite this page as:

Martin F. Gomon & Dianne J. Bray, Rhadinocentrus ornatus in Fishes of Australia, accessed 20 Apr 2024, https://fishesofaustralia.net.au/Home/species/4098

Ornate Rainbowfish, Rhadinocentrus ornatus Regan 1914

More Info

Distribution	Known from subtropical freshwaters of southern Queensland and northern New South Wales in coastal areas east of the Great Dividing Range between about Maryborough and Coffs Harbour. The species also occurs on sandy islands of southern QLD including Fraser Island, Moreton Island and North Stradbroke Island. Ornate Rainbowfish are found in freshwater creeks, larger streams, ponds and dune lakes in coastal wallum habitat. They are typically inhabit sandy coastal areas in slow-flowing acidic tannin-stained waters near submerged woody debris, grassy banks, and abundant submerged and emergent vegetation such as reeds and water lilies. The species also occurs in gallery rainforest habitats where it inhabits clear, slow-flowing streams with little or no vegetation. The Ornate Rainbowfish has a restricted and patchy distribution, and there is no gene flow between a number of fragmented populations.
Features	Meristic features: Dorsal fin spines/rays III-V; I, 11-15; Anal fin spines/rays I, 18-22; Pectoral fin rays 11-13 Body moderately elongate, laterally compressed, slender; greatest body depth in SL males 22.0-28.2, females 22.6-26.4; head length 22.9-28.8 in SL; snout length 5.9-7.6 in SL; eye large, diameter 8.1-12.7 in SL; caudal peduncle depth 6.8-10.3 in SL; caudal peduncle length 13.2-19.3 in SL; mouth terminal, oblique; lower jaw protruding; premaxillaries with a more or less distinct bend between the anterior horizontal portion and lateral part; jaw teeth conical to caniniform, one or more rows extending outside of mouth; vomer and palatines toothless. Scales relatively large, thin, cycloid with well-developed radii, horizontal rows on body at level of anal fin 8 or 9, vertical rows from upper corner of gill opening to caudal fin base 31 to 37. Two separate dorsal fins, first dorsal fin consisting of 3 to 5 slender, flexible spines; second dorsal fin composed of 11 to 15 segmented rays (first ray occasionally unsegmented); anal fin with a slender, flexible spine and 18 to 22 segmented rays; anal fin originates on anterior half of body; usually only last few dorsal and anal rays branched; branched caudal rays 10 to 13; males with more elongate rays in second dorsal and anal fins.
Size	To 5-6 cm SL, commonly to 4 cm SL.
Colour	Body semi-transparent silvery with shades of pink, blue or red; scale margins dark forming a network pattern; usually with a pair of dark stripes mid-laterally; iridescent neon blue patches on back and nape; fins generally reddish, often with dark rays. Ornate Rainbowfish are variable in colour depending on the geographic locality. A golden-yellow form occurs in the Key Hole Lakes system on Stradbroke Island.
Feeding	Omnivore - feeds on a variety of terrestrial and aquatic insects, crustaceans, algae, pollen and organic matter. Feeds mostly from the water's surface.
Biology	Males are more brightly-coloured than females and have more elongate anal fin and second dorsal-fin ray. During spawning, males also have a red nuptial stripe from the snout tip to the second dorsal fin. Oviparous - over several days, females deposit eggs with adhesive threads that stick to aquatic plants. Hatching occurs after 7-10 days. In captivity, individuals mature at about 9-12 months, and live to around 3-4 years. Page et al. (2004) found four genetically distinct populations of Rhadinocentrus ornatus: Byfield (Water Park Creek) south to Tin Can Bay and Fraser Island, QLD; Searys Creek (Rainbow Beach) QLD; Noosa River, QLD, south to Brunswick River, NSW, including Bribie, Moreton and Stradbroke Islands; Northern NSW south of Brunswick River.
Conservation	Populations are fragmented throughout their distribution range, and are under threat from the introduced and invasive Eastern Gambusia, Gambusia holbrooki, along with land clearing and habitat degradation. A phylogenetic study by Page et al. (2004) found that Rhadinocentrus ornatus exists in four fragmented populations corresponding to: Byfield (Water Park Creek) south to Tin Can Bay and Fraser Island Searys Creek (Rainbow Beach) Noosa River south to the Brunswick River (NSW), including Bribie, Moreton and Stradbroke islands Northern NSW, south of the Brunswick River.
Species Citation	Rhadinocentrus ornatus Regan, 1914, Trans. Zool. Soc. Lond. 20(6): 280. Type locality: Moreton Island, QLD.
Author	Martin F. Gomon & Dianne J. Bray

Ornate Rainbowfish, Rhadinocentrus ornatus Regan 1914

References

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Page, T., Ponniah, M., Sharma, S. & Hughes, J. 2006. Genetic distinctness of aquatic species on North Stradbroke Island: inferred from mitochondrial DNA sequence data from five freshwater species (Caridina spp., Rhadinocentrus ornatus, Nannoperca oxleyana and Macrobrachium tolmerum). Centre for Riverine Landscapes, Faculty of Environmental Sciences, Griffith University. Report to Department of Natural Resources, Mines and Water, May 2006.

Page, T.J., Sharma, S. & Hughes, J.M. 2004. Deep phylogenetic structure has conservation implications for ornate rainbowfish (Melanotaeniidae: Rhadinocentrus ornatus) in Queensland, eastern Australia. Marine and Freshwater Research 55: 165-172.

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Regan, C.T. 1914. Report on the freshwater fishes collected by the British Ornithologists' Union expedition and the Wollaston expedition in Dutch New Guinea. Transactions of the Zoological Society of London 20(6): 275-286.

Vaca, H.F. & White, C.R. 2010. Environmental modulation of metabolic allometry in ornate rainbowfish Rhadinocentrus ornatus. Biology Letters 6(1): 136-138.