Are Rainbow Trout Freshwater Fish? Knowing A Bow’s Habitat

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Trout swim in a river with rocks.

Rainbow trout are everywhere in the U.S. They fill lakes and rivers from the Great Lakes to the Ozarks to Oregon. This must mean they’re freshwater fish, right? Well, sort of. 

Many people interchange rainbow trout with steelhead, making their freshwater status confusing. Rainbow trout and steelhead are genetically the same fish, but their lifestyles lead to alternate habitats. Rainbow trout are freshwater fish, while steelhead inhabit saltwater and freshwater (they’re anadromous).

If you’re still confused, don’t worry. It took me too many years and too many Magic School Bus reruns to understand the topic. Let’s clarify. 

Defining Rainbow Trout and Steelhead

Rainbow trout and steelhead are technically the same fish from the Oncorhynchus mykiss species.

However, while steelhead migrate between freshwater and saltwater to spawn, rainbow trout reside in freshwater for as long as desired. Though you can find both in the same river, only the rainbow trout is a freshwater fish. 

  • Rainbow trout: born in freshwater, live in freshwater.
  • Steelhead: born in freshwater, but migrate between saltwater and freshwater.

Inland Rainbow Trout Habitat

Rainbow trout inhabit lakes, rivers, and ponds worldwide.

As an example, we have inland freshwater streams here in Wisconsin. Some streams have rainbow trout inhabiting their waters. With no realistic access to saltwater, they will remain rainbow trout.

However, if a river rainbow trout migrated to the Pacific Ocean, they would become steelhead.

Inland trout stream of western Wisconsin in late May.
Inland trout stream of western Wisconsin in late May

Can Rainbow Trout Become a Steelhead Trout?

Yes, and many do! If a rainbow trout migrates to saltwater from its freshwater home, then it becomes a steelhead.

Can Steelhead Trout Become a Rainbow Trout?

No, a rainbow trout’s change to steelhead is permanent. Once that rainbow trout migrates from freshwater to saltwater, its body will adapt. Even if it returns to its freshwater birthsite, its body keeps its steelhead traits.

Think of it this way: all steelhead begin as rainbow trout, but not all rainbow trout become steelhead. A rainbow trout is forever a steelhead after its initial freshwater-to-saltwater migration.

When Will Rainbow Trout Migrate To Saltwater?

If a rainbow trout migrates to saltwater, the journey usually occurs within the first three years of life. But this is a general rule.

Despite having access to saltwater, some rainbows will remain in their freshwater homes. Others do not have realistic access to the ocean and remain freshwater fish forever.

Fish go upstream at Ganaraska River, Port Hope, Canada.

Related Questions

What Is a Great Lakes “Steelhead?”

Ready to be more confused? The Great Lakes are a vast freshwater resource, and each lake is home to “steelhead.” If steelhead require migration between freshwater and saltwater, how is this possible?

Game and Fish Services introduced rainbow trout to the Great Lakes in the 1800s. These rainbows learned to migrate up their Great Lake tributaries. Today, locals call these giant rainbows “steelhead.”

Do you think these are true steelhead or just giant lake rainbows? Great Lake steelhead are freshwater fish.

What Is the Lifespan of a Rainbow Trout?

Most rainbow trout live for three to five years, but life expectancy can vary by region and habitat. As an example, the oldest recorded rainbow trout was 11 years old.

Steelhead can live up to 11 years, despite the stress and danger of repeated migrations. Their wisdom from repeated migrations may be what makes them so savvy and challenging to catch! Believe me; they can humble a fisherman pretty quickly!

How Old Is a 20-Inch Rainbow Trout?

A 20-inch rainbow trout is around five years old. Rainbow trout grow around four inches per year in their first three years. Then, if they are alive from three to six years old, their growth is rapid.

Having only caught a few trout over 20 inches, consider this a trophy.

Where Can I Find Rainbow Trout?

Rainbow trout prefer coldwater rivers and streams. These fisheries offer cool, clean, oxygenated water that trout need. But, because of rainbow trout’s durability, hatcheries raise and release rainbow trout into reservoirs, alpine lakes, and ponds.

Are There Saltwater Trout?

Spotted seatrout, often called speckled trout, are saltwater fish. Like salmon and steelhead, speckled trout are anadromous. They also migrate to freshwater for spawning.

Other saltwater trout include sand seatrout, gray trout, and silver trout. 

Do Steelhead Die After Spawning?

Unlike salmon, steelhead do not die after spawning. Instead, they can return to and from freshwater for their annual spawn. As long as they are alive, steelhead can return upriver.

Final Thoughts

Rainbow trout are freshwater fish and inhabit lakes, rivers, and streams worldwide. But a rainbow trout often ventures downstream to saltwater. At this point, they become a steelhead and migrate between saltwater and freshwater.

David Linsmeyer Avatar


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