Lake Eacham Rainbowfish, Melanotaenia eachamensis Allen & Cross 1982

Other Names: Lake Eacham Rainbow Fish

Summary:

A small silvery to bluish rainbowfish with a dark mid-lateral stripe, two fainter ventral bands, and reddish fins. Breeding males may be bronze to orange with a black margins on the dorsal and anal fins. They also have longer, more pointed and more brightly coloured fins than females.

The Lake Eacham Rainbowfish only occurs on the Atherton Tableland region of north Queensland.

Cite this page as:

Gomon, M.F. & Bray, D.J. 2024, Melanotaenia eachamensis in Fishes of Australia, accessed 05 Dec 2024, https://fishesofaustralia.net.au/home/species/3640

Lake Eacham Rainbowfish, Melanotaenia eachamensis Allen & Cross 1982

More Info

Distribution	Endemic to the upper reaches of the Barron, North Johnstone and South Johnstone River catchments at altitudes above 500 m above sea level; also in Koombooloomba Dam on the Tully River, Atherton Tablelands, Queensland. Individuals form schools amongst aquatic vegetation along the shallow edges of small freshwater creeks and crater lakes.
Features	Meristic features: Dorsal-fin rays V-VI, I, 9-13; Anal-fin rays I, 15-21; Pectoral-fin rays 11-14. Body laterally compressed, relatively elongate; greatest body depth 26.5% of SL; jaws about equal, oblique, premaxilla with an abrupt bend between the anterior horizontal portion and lateral part; jaw reaches back to front of eye; lips thin, except middle portion of upper lip bulbous; teeth conical with slightly curved tips, those in outer row generally stouter; teeth in upper jaw arranged in 2 irregular rows anteriorly, reduced to a single row posteriorly, outer row teeth exposed when mouth is closed; about 70-80 teeth in upper jaw; teeth in lower jaw in 3 or 4 irregular rows anteriorly, tapering to 1 or 2 rows posteriorly; about 140 teeth in lower jaw; vomerine teeth inconspicuous, 4-5 very small conical teeth; palatine with a band of 16-20 teeth arranged in a single row; head length 28.7 (27.6-32.5) in SL; snout length 8.6 (7.9-10.0) in SL; eye diameter 9.9 (8.6-12.1) in SL. Scales large, arranged in regular horizontal rows; body scales with smooth to slightly crenulate margins; horizontal scale rows 10-12; vertical scale rows 33-38; cheek scales 9-15. Two separate dorsal fins; first originates well ahead of anal fin origin; soft dorsal and anal fin rectangular in outline, the posterior rays somewhat elongate and pointed in males. Pelvic fin tips when depressed extending to about base of Ist or 2nd soft anal ray in mature males and not reaching anal fin origin in females; pectoral fins pointed; caudal fin moderately forked.
Size	To around 6.5 cm SL
Colour	Colour varies with locality but generally silvery or bluish to red-brown with dark midlateral stripe and 2-3 thinner dark bands below; fins transparent to bright red; fin margins of breeding males black.
Feeding	Feeds on aquatic and terrestrial invertebrates, and algae.
Biology	Spawning occurs from August to April with peak activity from August to November. Eggs are attached to fine root masses in well oxygenated areas. Eggs are small, demersal and adhesive. Larvae are small at hatching and lack a well-developed yolk sac. Larval development is complete at 11-14 mm TL.
Conservation	EPBC Act 1999 : Endangered IUCN Red List : Vulnerable Originally described from Lake Eacham, an isolated crater lake on the Atherton Tablelands, Queensland. The Lake Eacham Rainbowfish is presumed extinct in the Lake due to predation by illegally translocated native fishes. During the 1980s a number of native fishes were translocated into the lake - Barred Grunter (Amniataba percoides), Mouth Almighty (Glossamia aprion), Bony Herring (Nematalosa erebi) and Seven-spot Archerfish (Toxotes chatareus). By 1987 these translocated species were abundant and the Lake Eacham rainbowfish could not be found (Barlow et al., 1987). In some areas, the species naturally hybridises with the eastern rainbowfish (Melanotaenia splendida), and it is important to conserve the most genetically pure populations (Zhu et al., 1998).
Remarks	Although thought to be extinct in 1987, the Lake Eacham Rainbowfish was rediscovered in the private collections of aquarists (Caughey et al., 1990). The species was subsequently found to have a wider distribution, with populations surviving in the wild in the upper Barron and Johnstone River catchments.
Etymology	The species is named eachamensis after the type locality, Lake Eacham.
Species Citation	Melanotaenia eachamensis Allen & Cross, 1982, Rainbowfishes of Australia and Papua New Guinea: 45. Type locality: Lake Eacham, Atherton Tableland, N QLD.
Author	Gomon, M.F. & Bray, D.J. 2024

Lake Eacham Rainbowfish, Melanotaenia eachamensis Allen & Cross 1982

References

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