Australian Grayling, Prototroctes maraena Günther 1864

Other Names: Cucumber Fish, Cucumber Herring, Cucumber Mullet, Cucumberfish, Cucumber-fish, Grayling, Yarra Herring

Summary:

A silvery freshwater fish with a small adipose fin on the rear of the back, a keel along the belly, no lateral line and a horny sheath around the lower jaw.
Adult Australian Grayling inhabit freshwater rivers and streams. During autumn, they undertake large migrations to spawn in the lower reaches of rivers. The newly hatched larvae are swept out to sea and migrate back to estuaries after about 6 months. The species has a distinct cucumbery smell.

Cite this page as:

Gomon, M.F. & Bray, D.J. 2020, Prototroctes maraena in Fishes of Australia, accessed 19 Jan 2025, https://fishesofaustralia.net.au/Home/species/3634

Australian Grayling, Prototroctes maraena Günther 1864

More Info

Distribution	Endemic to coastal rivers and streams of southeastern Australia, from the Grose River (New South Wales) to the Hopkins River (Victoria), including coastal in Tasmania and King Island in Bass Strait. Historically the species occurred as far north as the Hunter River in New South Wales, with a single record from Ewens Ponds near Port MacDonnell in the far south-east of the South Australia. The Australian Grayling is known to occur at elevations up to 700 m asl and is able to move large distances inland. Adults prefer moderate to fast-flowing water in rivers and streams, usually in cool clear waters below altitudes of 200 m, although they have been recorded above 1000 m in Victoria. They often occur in pools with gravelly substrates, and may form large schools, especially before spawning. The Australian Grayling is diadromous, migrating between rivers and coastal waters during its life cycle. The species on weirs to enable free access to a range of freshwater, estuarine and marine coastal habitats.
Features	Dorsal fin 9-13; Anal fin 16-20; Pectoral fin 12-14; Pelvic fin 6; Vertebrae 62-65. Body long and slender, compressed; head small, conical with bluntly rounded snout; eye of moderate size; mouth slightly oblique, small; gape extending back to beneath eye; lower jaw shorter than upper jaw, tapering to a fine point; gill rakers on first arch 20-26; teeth in upper jaw blunt in a comb-like row; weak abdominal keel present in front of anus. Scales thin, cycloid of moderate size, 68-86 in lateral series; lateral line absent. Dorsal fin in about middle of back, behind ventral fin; small adipose fin present behind dorsal; ventral fins on middle of belly, small, rounded; caudal fin forked; anal fin beneath space between dorsal and adipose fin; pectoral fins well forward, low, small, triangular.
Size	Maximum size to 33 cm TL but commonly to 17-19 cm TL.
Colour	Dusky brown to greenish-brown above, greenish to bronze midlaterally and silvery-white to yellowish below. Sometimes has a steely-blue mid-lateral band and dark spot on the caudal fin base. Fins greyish-white.
Feeding	Omnivore - feeds mainly on algae and detritus, and also on a variety of small aquatic invertebrates, including microcrustaceans, insects and their larvae. Australian Grayling have highly specialised dentition that allows them to comb filamentous algae growing on rocks, and a long specialised gut to help digest algae.
Biology	The Australian Grayling is an amphidromous species. Adults inhabit freshwater rivers and streams, and undertake spawning migrations to the lower reaches of rivers between February and May - usually coinciding with increased river flows. The species is highly fecund, and females spawn on average 47000 eggs in autumn (April-May) following high water flows and a drop in temperature. The demersal eggs sink to the bottom downstream of where they are spawned. Larvae hatch at 6-7 mm TL after 10-20 days, and are carried downstream into estuaries and out to sea. They spend 4-6 months at sea before migrating back into freshwater as juveniles.
Fisheries	Once popular with recreational anglers in the late 1880s to early 1900s, the species is now protected - although juveniles are occasionally caught as bycatch in the Tasmanian whitebait fishery.
Conservation	IUCN Red List: Near Threatened EPBC Act 1999: Vulnerable NSW: Listed as Endangered (Fisheries Management Act 1994 (New South Wales) TAS: Listed as Vulnerable (Threatened Species Protection Act 1995 (Tasmania) VIC: Listed as Threatened (Flora and Fauna Guarantee Act 1988 (Victoria)
Remarks	Australian Grayling may form aggregations below barriers to upstream movement such as weirs and waterfalls. Exudes a cucumber-like smell when freshly caught. Researchers have found that adult Australian Grayling in the Thomson River, Victoria, undertake downstream spawning migrations (up to 140 km) to the lower river to coincide with environmental flow releases (Amtstaetter et al. 2015).
Etymology	The specific name maraena is from the German word Maräne, the common name used for whitefish, salmonids of the genus Coregonus. Günther describes the genus Prototroctes as having 'the general habit of a Coregonus'.
Species Citation	Prototroctes maraena Günther 1864, Cat. fishes Brit. Mus. 5: 382. Type locality: Southern Australia.
Author	Gomon, M.F. & Bray, D.J. 2020
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

Australian Grayling, Prototroctes maraena Günther 1864

References

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