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Gadopsis marmoratus
Gadopsis marmoratus — juvenile, southern form, Badger Creek near Healesville, Vic — photo © Rudie Kuiter

Gadopsis marmoratus

Richardson, 1848

River Blackfish

Species Summary

The more widespread of Australia’s two freshwater blackfishes, Gadopsis marmoratus occurs in rivers and streams of Victoria, northern Tasmania, New South Wales, South Australia and the upper reaches of the Murray River system into Queensland. Colour pattern shows best in juveniles; large adults tend to darken with age.

Taxonomy

What is presently treated as one variable species may in fact be several. Molecular work has found clear differences between a “northern” form (the true Gadopsis marmoratus, typical of the Murray River system) and a “southern” form from the slopes of the Great Dividing Range, once separately described as G. gibbosa from Gippsland and possibly still valid; a third form, G. fuscus from South Australia, is currently synonymised with the northern form too. The two confirmed forms have never been found sharing the same water. A white margin on the fins seems to mark the northern form, though populations in Creighton Creek (part of the Goulburn/Murray catchment) lack it, so the picture is not yet fully resolved — more species could well be involved.

Remarks

The genus name itself carries an old grammatical quirk worth knowing: Richardson and later Sanger both published their species names in the masculine (“marmoratus”, “bispinosus”), but since Gadopsis is a feminine genus and the species names are Latin adjectives, strict grammatical agreement calls for the feminine forms marmorata and bispinosa instead — a distinction some recent sources now follow, though this site keeps the long-familiar masculine spelling.

Compiled for Home of the Rainbowfish from ANGFA sources: R. Kuiter, “Freshwater Blackfishes”, Fishes of Sahul 23, 2009, pp. 499–500; and “Gadopsis”, In-Stream 14(4), August 2005, p. 3.

References