Rainbow Trout

Common Name: Rainbow Trout
Scientific Name: Oncorhynchus mykiss

How to Identify a Rainbow Trout

Rainbow trout are highly variable fish. Their coloration can change with habitat, age, sex, spawning condition and whether the fish lives permanently in freshwater or follows a migratory life history.

A typical freshwater rainbow trout has an olive, blue-green or grayish back that transitions to silvery sides and a lighter belly.The most recognizable feature is usually the: pink, rose or reddish band running along the side of the body. That band may be vivid on some fish and faint on others.

Spots

Rainbow trout usually carry numerous small dark spots across: the upper body ,back, dorsal fin, and especially the tail A heavily spotted tail is one of the most useful field clues.

Body Shape

Rainbows are generally streamlined, athletic-looking fish built for current and sustained swimming.

Lake or reservoir fish can become deeper-bodied as they grow.

Mouth

The mouth is typical of a predatory salmonid, though most rainbows do not develop the massive head and jaw proportions sometimes seen in large predatory Brown Trout.

Rainbow Trout vs. Brown Trout

Rainbow trout generally show:

pink/red lateral coloration, dense dark spotting, spots across the tail

Brown trout generally show:

brown-to-golden body coloration, dark and red/orange body spots, less heavily spotted tail

Rainbox Trout vs. Brook Trout

Rainbow trout lack:

brook-trout vermiculations, blue-haloed red spots, white-edged orange lower fins

Rainbow Trout vs. Steelhead

This is especially important.

Steelhead are Rainbow Trout.

Steelhead often appear more silver and streamlined than resident river rainbows. They are not a separate species.

They are the migratory form of Oncorhynchus mykiss that spends a substantial portion of its life in large lake or marine environments before returning to tributaries to spawn.

Range

Where Rainbow Trout Live

Rainbow trout are native to the Pacific drainage of North America and portions of northeastern Asia.

Their native North American distribution extends from parts of Alaska and western Canada south through Pacific coastal and interior drainages of the western United States.

Humans have introduced Rainbow Trout far beyond that original range.

Today, they support fisheries throughout much of the United States and in many countries around the world.

Rainbow trout now occur in:

cold streams and rivers
tailwaters
lakes and reservoirs
Great Lakes systems
stocked ponds
large migratory fisheries

Some populations reproduce naturally. Others depend partly or almost entirely on stocking.

Steelhead

The species also includes migratory populations commonly called steelhead.In their native Pacific range, steelhead migrate between freshwater and the ocean. In the Great Lakes, Rainbow Trout can develop a similar migratory life history between tributaries and the lakes.

The national Rainbow Trout page owns the fish itself. State- and fishery-specific Rainbow Trout and steelhead questions belong in geographic supporting content.

Habitat

Rainbow Trout Habitat

Rainbow trout occupy a broader range of coldwater environments than many anglers realize.

They can thrive in:

small streams
large rivers
tailwaters
lakes
reservoirs
Great Lakes tributaries

In streams and rivers, rainbows commonly use:

riffles
runs
current seams
pool heads
pockets behind structure
deep holding water
edges between fast and slow current

They often hold where moving water delivers food efficiently.

That can make them especially associated with active current compared with fish that rely heavily on dense overhead cover.

In lakes and reservoirs, Rainbow Trout may use:

shorelines
points
drop-offs
open water
structure
depth bands containing suitable temperature and forage

Some rainbows roam widely while following prey. Others relate more consistently to structure or thermal habitat. Migratory Great Lakes fish add another layer.

They may spend substantial time in large open water and then enter tributaries, where current, depth, gravel and migration routes become critical habitat. A good Rainbow Trout habitat question is therefore not simply: “Is the water cold?”

It is: Does the water provide the temperature, oxygen, food and physical habitat this population needs at this point in its life?

Rainbow Trout Behavior

Rainbow trout are active, adaptable feeders. In moving water, they commonly position themselves where current delivers food without forcing them to fight the strongest flow continuously.

That can mean holding: behind rocks, along seams, at the head of pools, near riffle transitions, or in softer water beside a stronger food-delivery lane.

Compared with some highly cover-oriented Brown Trout, rainbows can be more willing to occupy open feeding water when conditions are favorable.

They are also famous for their fighting behavior. Hooked rainbows frequently make:

fast runs

direction changes

surface jumps

which is one reason they are such popular sport fish.

Movement

Rainbow Trout can move substantially in response to: temperature, flow, food, spawning, and seasonal habitat changes.

Migratory forms take this much farther.

Great Lakes and ocean-run steelhead may travel between enormous feeding environments and relatively small tributaries.

Feeding Behavior

Rainbows can switch quickly between food sources. One moment they may be feeding on drifting nymphs. During a hatch they can turn their attention to emerging or adult insects.

In lakes they may cruise and follow plankton, insects, baitfish or other forage. That flexibility is a major reason Rainbow Trout respond to such a wide range of fishing methods.

Seasons

Rainbow Trout Through the Seasons

Spring

Spring is especially important for Rainbow Trout because many populations spawn during this part of the year. Fish may move toward tributaries, riffles or other suitable spawning habitat as water conditions change. Outside active spawning behavior, rising temperatures and increasing insect activity can also increase feeding.

Summer

In properly cold water, rainbows can remain active throughout summer. They may feed on: aquatic insects, terrestrials, and available baitfish or other forage. As water warms, fish may seek colder or more oxygenated habitat. In lakes, this can mean moving deeper. In rivers, it may mean shifting toward cooler tributaries, deeper runs or thermal refuge.

Fall

Cooling water can increase the amount of suitable habitat available to Rainbow Trout. Fish may redistribute as temperatures moderate and forage changes. Great Lakes rainbow/steelhead populations may also enter tributaries during seasonal migrations depending on the particular strain and fishery.

Winter

Rainbow Trout continue feeding in winter, but activity often slows. In rivers, fish may favor: deeper pools, slower runs, and energy-efficient holding water. In lakes, Rainbow Trout may remain active beneath the ice and can provide important winter fisheries.

The actual seasonal pattern depends heavily on whether the population is:

resident stream trout
lake-dwelling trout
stocked trout or migratory steelhead.

That distinction is one of the defining differences of this species.

spawning

Rainbow Trout Spawning

Rainbow Trout generally spawn in spring, although exact timing varies with geography, water temperature and population. That is a major biological difference from Brown Trout and Brook Trout, which are fall spawners.

Spawning fish seek areas with:

clean gravel
moving, oxygenated water
appropriate depth and current

Females excavate nests called redds by moving gravel with their tails. Eggs are deposited into the redd, fertilized by males and covered with gravel. Developing eggs rely on water moving through the substrate to provide oxygen.

Migratory Rainbow Trout / Steelhead

Steelhead add another layer. Adults migrate from larger feeding waters into rivers and tributaries for spawning. The timing of those migrations varies dramatically among waters and populations.

Great Lakes steelhead may enter tributaries during different portions of the year, even though spawning itself is generally associated with the spring period.