Steelhead and Rainbow Trout – What’s the Difference?

By Spencer Durrant

Every steelhead is a rainbow trout, but not every rainbow trout is a steelhead.

While that’s technically true, it doesn’t really answer the question, does it?

That’s what makes discussing steelhead and rainbow trout a bit tricky, especially for folks who are new to angling. As we dive into the differences between steelhead and rainbow trout, keep in mind the first line of this post. It’ll make more sense as we move on.

Rainbow Trout

Rainbow trout (Oncorhynchus mykiss) were originally only found in rivers and lakes that drain into the Pacific Ocean, from Mexico up to Alaska, and west to Kamchatka, Russia. Since rainbow trout are so easily farmed, and adapt well to different waterbodies, they’ve been introduced across the world. Take a look at this graphic:

You’ll find rainbow trout in every state in America, and throughout Canada, as well. Rainbows are popular game fish in many fly fishing rivers, including places like the Madison and Henry’s Fork Rivers.

Appearance

Rainbows get their name from the bright pink stripe down their flanks. They usually have dark green backs, with irregular black spots across the entire body.

The coloration of rainbow trout depends largely on where they live and what they eat. Sometimes, you’ll catch rainbows that look slightly “washed out” compared to other fish.

Steelhead

Steelhead are native to rivers and streams that drain into the Pacific Ocean. NOAA lists both steelhead and rainbow trout with the same genus species – Oncorhynchus mykiss. 

Steelhead are endangered throughout their native range, with many groups – like Wild Steelhead Coalition – fighting to preserve the few runs of these fish that remain.

Appearance

Steelhead are very similar in appearance to rainbow trout, but usually don’t have the pronounced coloration that rainbows do. Steelhead tend to have a silvery body with dark backs.

What’s the Difference?

So, if steelhead and rainbow trout are the same genus species, then what’s so different about them? Why are there groups fighting to preserve steelhead, but we don’t hear stories about protecting rainbow trout?

Well, the main difference comes down to where these fish live. Steelhead are sea-run fish (the scientific word is anadromous). They’re born in freshwater, then migrate out to sea, where they spend time growing before returning to spawn. Unlike other sea-run fish, however, steelhead don’t die immediately after spawning. They can return and spawn in the river they were born in multiple times throughout their lives.

Rainbow trout never leave freshwater. They stay in lakes, rivers, and streams for their entire lives. It’s also rare for rainbow trout to reach the massive sizes of some steelhead.

Steelhead fishing is quite difficult, but can produce one of those stories you tell for a lifetime. Check out the video below for a good idea of what a day (or week) searching for Steelhead might look like.

Conservation

Due to habitat loss and degradation, as well as declining water quality throughout their native range, steelhead are facing extinction. Each year, fewer fish return from their time at sea to spawn in fresh water, putting the survival of the species in jeopardy. In the Pacific Northwest, steelhead and salmon use many of the same streams and rivers for spawning, which is why so many groups are pushing for conservation of both these fish throughout the Columbia River basin.

Have you ever caught a steelhead? Tell us your story in the comments!