pdf version - South Dakota Department of Game, Fish and Parks

TROUT (family Salmonidae)
Rainbow Trout
Oncorhynchus mykiss
Quick key characteristics: The rainbow trout is found in cold-water habitats.
It has small scales, soft fi ns with short bases, including an adipose fi n. It has a
forward-facing mouth, a relatively blunt snout (compared to other trout), and
its body is taller than wide.
Similar species in South Dakota: other trout and salmon
Identifi cation: The combination of (1) small, abundant dark spots distributed
relatively evenly over a lighter background across the head, body, and fi ns, (2)
tail (caudal) fi n rounded (not pointed), (3) white margins on paired (pectoral,
pelvic) fi ns, (4) white “gums” at the base of jaw teeth, (5) a relatively short
anal fi n, and (6) a pink or red lateral stripe distinguishes rainbow trout from
other trout and salmon in South Dakota.
Range: The rainbow trout is native in Asian and North American rivers that
empty into the northern Pacifi c Ocean and in some “closed” basins of western
North America. It has been introduced into cold-water habitats worldwide.
In South Dakota, it has been stocked in impoundments and tailwaters of
the Missouri River, ponds in the western part of the state, and streams and
impoundments of the Black Hills. Rainbow trout are also used in put-andtake
fi sheries in urban areas throughout South Dakota.
Items of interest:
• Spawns in spring, but natural reproduction is limited in South Dakota,
so most populations are maintained
by stocking
• Feeds primarily on insects and
crustaceans, but larger individuals
may eat fi sh
• Can reach 24 in. in streams, but larger
in rivers, lakes, or impoundments
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