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Rainbow Trout Facts and Species Info

rainbow trout

oncorhynchus mykiss

The rainbow trout is a hardy fish that thrives in regions across the United States and other countries, making it one of the world’s most popular game fish. There are various rainbow trout species, some of which live in freshwater while others live in oceans.

Unfortunately, soil erosion, pollution, logging, and microscopic parasites have profoundly detrimental effects on the species’ population, landing a few sea-faring species on endangered lists. Still, many freshwater species continue to thrive. The plentiful information we have on this popular game fish can help anglers like you enjoy a rainbow trout catch of your own.


Species Description

The rainbow trout (Oncorhynchus mykiss) have shiny, colorful skin that leads to their colorful name. Its primary body color is a silvery-green, but iridescent purples, blues, and pinks shine through in different lighting, making the fish appear as though it’s rainbow-colored. 

Rainbow trout come from the same family as salmon and even have a similar taste. Rainbow trout are native to northern areas of the United States near the Pacific coast. However, hatcheries have introduced them to other regions because of their ability to thrive in virtually any environment. 

The Rainbow trout can live as long as 11 years, but most live an average of 5 to 7 years. The longer end of the lifespan is usually reserved for freshwater varieties. 

The average Rainbow trout reaches about eight pounds, although some outliers have reached 40 pounds or more. Expect these fish to be between 20 and 30 inches long in the wild but slightly smaller in hatcheries. Rainbow trout have a torpedo-like shape, making them wider in the midsection than the head or tail.

The species as a whole is not endangered because they’re so widely introduced to water bodies across the world. Some oceanic species of Rainbow trout, known as steelhead trout, are currently on threatened and endangered lists.



How to Identify a Rainbow Trout

The tell-tale mark of a Rainbow trout is its pink stripe that runs across its body. This stripe occurs in both freshwater and saltwater species.

You can also spot a Rainbow trout by its multi-colored skin. The colors are easy to see in and out of the water, depending on the lighting. However, some Rainbow trout aren’t as iridescent as others, as color patterns typically rely on the fish’s maturity and habitat.

Another mark of a Rainbow trout is its spots. Most of these fish have small black dots all over their bodies. The spots act as a defense mechanism, helping the fish blend into rocks on the water’s floor.


rainbow trout identification


History of the Rainbow Trout

The Rainbow trout is a native of Northwestern America that people have since introduced to water bodies worldwide, including the United Kingdom and South America, beginning in the late 1800s. Rainbow trout thrive in freshwater with cool temperatures, but they’re known for adapting to wide temperature ranges.

The introduction of the Rainbow trout into hatcheries and natural water bodies has caused a massive fish population, leading to them becoming a nuisance species in some areas. The spike in population led to the Rainbow trout being one of the most popular game fish globally.


World Record

The current world record holder for the largest Rainbow trout catch is Sean Konrad, an angler with a strong love of fishing in his family. In fact, the previous world record went to his twin brother, Adam, who held it for two years prior.

The catch happened on September 5th, 2009, in Diefenbaker Lake in Saskatchewan, Canada, the same place where Adam found his massive trout. Sean’s catch was a whopping 48 pounds.

Some have called Sean’s record into question, though. Diefenbaker Lake is known for its genetically-modified Rainbow trout that causes them to expend energy on massive growth rather than reproduction. 

The International Game Fish Association (IFGA) has defended the record, noting that it doesn’t place natural and genetically-modified fish into separate categories for records.


large rainbow trout


Life Cycle

Whether they’re freshwater or sea dwellers, all Rainbow trout return to the stream in which they were born to reproduce. Steelhead trout will usually attempt to swim back to the sea after spawning, but some may linger behind in freshwater.

Rainbow trout can begin to spawn at three years old, and the reproduction cycle typically begins in early to late spring, between January and June in most areas. Females deposit their eggs into nests on the stream floor, known as redds, while males deposit sperm into the nest of eggs to fertilize them.

Between 20 and 80 days later, the eggs hatch into alevins. The alevins remain in their nest for about three more weeks until they develop enough to swim and feed. Each fish is a fry at this stage, becoming a fingerling when it grows between two and five inches and a parr when it develops it’s distinctive coloring and spots.


spawning rainbow trout



The ideal home for a Rainbow trout is in cool, freshwater streams with plenty of gravel rock and natural shading. These adaptive fish can handle cold and warm water, though, if necessary. Therefore, it’s not uncommon to see them anywhere from Argentinian rivers’ warmer waters to Lake Superior’s cold waters.

You can currently find Rainbow trout in every state in the United States, either in natural water bodies or hatcheries. Rainbow trout also populate countries worldwide, including Canada, Russia, Chile, Denmark, and Italy.


As a rule, Rainbow trout are not picky when it comes to feeding. Their love for food is one reason they can adapt so well to different water bodies and environments. Typically, Rainbow trout enjoy eating:

  • Aquatic insects, like mayflies and caddisflies
  • Land insects that get into the water, like crickets and ants
  • Plankton
  • Freshwater shrimp
  • Fish carcasses
  • Minnows
  • Crustaceans 
  • Fish eggs, including the eggs of other rainbow trout

Steelhead varieties of Rainbow trout have a similar diet. But Steelheads tend to grow larger than freshwater Rainbow trout and may eat larger items, like small fish and mice.


trout eating flies


Threats to the Rainbow Trout Species

Despite overpopulating some areas, Rainbow trout families aren’t without threats. Climate change is one problem that threatens the cooler temperatures that Rainbow trout prefer, especially in warmer regions like California.

Environmental factors that threaten many fish and wildlife also affect Rainbow trout populations and their ability to migrate. These factors include soil erosion, pollution, vegetation loss, and habitat modification.

Whirling disease also targets Rainbow trout and other salmonids. The condition happens when a parasite infects a fish, causing skeletal deformities that can make it challenging or impossible to feed or swim normally, leading to fatality.

Because whirling disease-causing parasites can spread between populations, anglers must know what to look for when fishing for Rainbow trout. The best way to stop the spread is to avoid bringing live fish into other water bodies. You should also dispose of all fish parts in the garbage rather than the water. 


How to Catch a Rainbow Trout

Rainbow trout respond best when they sense food is near, making fly fishing a popular way to catch them. Using an artificial fly as bait, you can fish in still waters during almost any time of year to successfully round up Rainbow trout.

For most Rainbow trout, especially those in ponds and small lakes, a small fishing hook, ultralight tackle and light line is best. Texas Parks and Wildlife also recommends using a three-way rig to keep your fish bait off the bottom of the water floor.


catching a rainbow trout


Where to Catch a Rainbow Trout

Rainbow trout are plentiful in many regions, so it shouldn’t be too much of a challenge to find them when fishing. Look in waters that are between 45 and 65 degrees for the best chances of spotting these fish. Hang around waters with plenty of food for Rainbow trout, like minnows and aquatic insects, and places to hide, like aquatic plants and rocks.

During warm months, you’re likely to find Rainbow trout in deeper waters as they try to keep themselves cool while staying protected from other predators. Rainbow trout commonly swim near logs, rocks, stream inlets, and anywhere that food is plentiful.


How to Eat a Rainbow Trout

grilled rainbow trout

Rainbow trout has a similar flavor to salmon, although those you catch in freshwater streams and ponds won’t taste as seafood-like. Rainbow trout tends to have a more mild, nutty flavor than salmon, but it works well as a substitute for salmon in many dishes.

Although there are several ways to enjoy Rainbow trout, a simple, pan-seared dish, like this one from the New York Times Cooking, is one of the most common ways to eat it. 

Dip the fish in flour seasoned with salt and pepper before frying it in olive oil for two to three minutes on each side. Add a squeeze of fresh lemon juice just before serving. Serve with a side of lemon angel hair pasta, fresh veggies, or roasted potatoes.

Rainbow trout is a favorite of anglers because of its availability and fresh flavors. Now, you’re armed with all the must-know information you need to catch and enjoy this popular fish.


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