Rainbow Trout, Oncorhynchus mykiss (Walbaum 1792)

Other Names: Bow, Rainbow, Steelhead Trout

Rainbow Trout, Oncorhynchus mykiss. Source: Mike Cline / Wikimedia Commons . License: Public Domain

Variable in colour - fish in lakes are mostly greenish or steely-blue above, with a silvery-white belly, usually a prominent rosy-pink stripe along the sides and small black spots on the body and fins. Individual fish in lakes may be silvery without a pink stripe. Juveniles often have dark blotches along the sides that disappear with growth.
Native to western coastal drainages of North America, Rainbow trout were first introduced to Australia from New Zealand in 1894. Although an extremely popular freshwater gamefish, the introduction of Rainbow Trout into our freshwaters has severely impacted native fish populations.

Cite this page as:
Martin F. Gomon & Dianne J. Bray, Oncorhynchus mykiss in Fishes of Australia, accessed 17 Jun 2024, https://fishesofaustralia.net.au/home/species/2083

Rainbow Trout, Oncorhynchus mykiss (Walbaum 1792)

More Info


Introduced to Australia's cooler freshwaters. Occurs west of the Great Dividing Range from Browns Creek, near Killarney, south-eastern QLD (28°20'S, 152°16'E), to Browns Creek, Otway Ranges, VIC (38°46'S, 143°24'E), to the Adelaide Hills, SA, and in south-western WA. Native to North America found in temperate lakes and streams with gravel bottoms in cool (10°-22°C), well oxygenated water.

Rainbow Trout are migratory with adults of non-land locked populations living in the sea and returning to clear freshwater streams to breed.


Meristic features: Dorsal fin 10-12; Anal fin 8-12; Caudal fin 19; Pectorall fin 11-17; Pelvic fin 9-10; Gill rakers on first arch 16-22

Body relatively deep and compressed; head length about 20% TL; mouth large, extending to below eye, terminal, slightly oblique; eye moderately large, diameter 12-25% HL; small canine teeth on jaws, vomer, palatine and tongue. Scales small, cycloid; 100-160 along lateral line. Males have enlarged jaws with the tip of the lower jaw forming a kype, as in brown trout.

Dorsal fin midway along back, square edged; fleshy adipose fin behind dorsal; anal fin short-based, below adipose fin, squarish; caudal fin truncate to slightly forked; ventral fins abdominal, relatively small, square to rounded with axillary process at base; pectoral fins long, rounded to somewhat pointed, inserted low on sides


To 120 cm TL, commonly to 40-50 cm.


Colour is variable, lake fish predominantly silvery; back dark, either greenish-olive or a deep steely-blue with many small, dark, round spots on back and upper sides. Lower surfaces silvery-white. Dorsal fin and tail dark olive-grey with many small, dark spots. Often a rosy-pink stripe along sides and on gill covers. River fish and those on spawning migrations become more intensely coloured; the pink stripe intensifies to deep crimson, lower fins become reddish, and lower sides and belly a deep smoky-grey. Spots on sides become bolder and more conspicuous.


Feeds on freshwater insect larvae, crustaceans, snails, small fish, and an opportunistic feeder on terrestrial insects. Generally feeds close to the surface.


Mature at 2-3 years and spawn from July to October. Females build a nest ('redd') in the gravel where they deposit large (4-5 mm diameter) slightly adhesive demersal eggs. The larvae hatch in 3-12 weeks depending on water temperature.


An extremely popular freshwater gamefish introduced for recreational angling. Fisheries agencies have stocking programs for Rainbow and other trout species. Millions of salmonids are released annually from Govt and private hatcheries.


Rainbow and Brown trout have seriously impacted the distribution and abundance of the native fishes in Australia, especially galaxiid species - causing localised extinctions.


Rainbow and Brown trout are often infested with found with the parasitic copepod Lernaea sp. which is often attached around the fins. Fish may be heavily affected during times of heat stress, and often have large obvious red sores.

Species Citation

Salmo mykiss  Walbaum, J.J. (1792). Petri Artedi 3: 59. Type locality: Kamchatka, Russia.


Martin F. Gomon & Dianne J. Bray

Rainbow Trout, Oncorhynchus mykiss (Walbaum 1792)


Allen, G.R. 1982. Inland Fishes of Western Australia. Perth : Western Australian Museum 86 pp. 6 figs 20 pls.  as Salmo gairdnerii)

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia. Perth : Western Australian Museum 394 pp.

Arthington, A.H. 1991. Ecological and genetic impacts of introduced and translocated freshwater fishes in Australia. Can. J. Fish. Aquat. Sci. 48(Suppl. 1): 33-43.

Cadwallader, P.L. 1996. Overview of the Impacts of Introduced Salmonids on Australian Native Fauna. Australia Nature Conservation Agency, Canberra.

Cadwallader, P.L. & Backhouse, G.N. 1983. A Guide to the Freshwater Fish of Victoria. Melbourne : F.D. Atkinson Government Printer 249 pp. figs. (as Salmo gairdneri)

Crowl, T.A., Townsend, C.R., McIntosh, A.R. 1992. The impact of introduced brown and rainbow trout on native fish: the case of Australasia. Reviews in Fish Biology and Fisheries 2: 217-241.

Farrington, L.F., Austin, C.M., Burridge, C.P., Gooley, G.J., Ingram, B.A. & Talbot, B. 2004. Allozyme diversity in Australian rainbow trout, Oncorhynchus mykiss (Walbaum). Fisheries Management & Ecology 11: 97-106

Gomon, M.F. 1994. Families Halosauridae, Notacanthidae, Clupeidae, Engraulidae, Gonorynchidae, Plotosidae, Salmonidae. pp. 215-231 figs 192-206 in Gomon, M.F., Glover, C.J.M. & Kuiter, R.H. (eds). The Fishes of Australia's South Coast. Adelaide : State Printer 992 pp. 810 figs.

Grant, E.M. 2002. Guide to Fishes. Redcliffe : EM Grant Pty Ltd 880 pp. (as Salmo gairdneri)

Kailola, P.J., Williams, M.J., Stewart, P.C., Reichelt, R.E., McNee, A. & Grieve, C. 1993. Australian Fisheries Resources. Canberra : Bureau of Resource Sciences and the Fisheries Research and Development Corporation 422 pp.

Lintermans, M. 2004. Human-assisted dispersal of alien freshwater fish in Australia. New Zealand Journal of Marine and Freshwater Research 38: 481-501.

Lintermans, M. 2007. Fishes of the Murray-Darling Basin — An Introductory Guide. Canberra : Murray-Darling Basin Commission 157 pp. 

MacCrimmon, H.R. 1971. World distribution of rainbow trout (Salmo gairdnerii). Journal of the Fisheries Research Board of Canada 28(5): 663-704 figs 1-7 (world introductions, as Salmo gairdnerii)

McDowall, R.M. (ed.) 1996. Freshwater Fishes of South-eastern Australia. Sydney : Reed Books 247 pp.

McDowall, R.M. 2006. Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes? Rev Fish Biol Fisheries 16: 233–422.

Merrick, J.R. & Schmida, G.E. 1984. Australian Freshwater Fishes Biology and Management. Sydney : J.R. Merrick 409 pp. figs 280 col. figs. (as Salmo gairdnerii)

Prokop, F. 2002. Australian Fish Guide. Croydon South, Victoria : Australian Fishing Network 256 pp.

Raadik T.A Family Salmonidae Trouts, Salmon In Gomon, M.F., Bray D., & Kuiter, R.H. (eds) (2008). The Fishes of Australia's South Coast. Adelaide : State Printer 928 pp.

Smith, G.R. & Stearley, R.F. 1989. The classification and scientific names of rainbow and cutthroat trouts. Fisheries (Bethesda) 4(1): 4-10.

Walbaum, J.J. 1792. Petri Artedi renovati. Part 3. Petri Artedi sueci genera Piscium in quibus systema totum ichthyologiae. Grypeswaldiae 723 pp. 3 pls 

Western Australia Fisheries. 2002. The translocation of brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) into and within Western Australia. Fisheries Management Paper No 156. Dept of Fisheries WA.

Quick Facts

CAAB Code:37094003

Behaviour:Migratory - breeds in freshwater

Fishing:Popular angling fish

Habitat:Freshwater & marine

Max Size:120 cm TL


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