Many people confuse salmon and trout since they belong to the same family, Salmonidae. To make matters worse, they also have a similar appearance.
Rainbow trout and salmon are different fish with general variations. Most believe that rainbow trout are freshwater and salmon migrate to saltwater, but this logic doesn’t hold up in all situations.
Differences Between Salmon And Rainbow Trout
Technically, rainbow trout only belong to the genus Oncorhynchus, while salmon comprise Oncorhynchus and Salmo genera. In other words, rainbow trout are not salmon but share the same genus with some salmon species.
While there are differences between rainbow trout and salmon, there are also exceptions to these differences. Here are some general distinctions between rainbow trout and salmon.
Difference #1: Rainbow trout is a specific species while salmon is an umbrella term for various fish.
- Exception: “Rainbow trout” is an interchangeable term with steelhead since steelhead and rainbow trout are the same fish.
Difference #2: Rainbow trout reside in freshwater, and salmon are anadromous (they migrate between fresh and saltwater).
- Exception: Steelhead trout, which begin as rainbow trout, are also anadromous.
Difference #3: Salmon die after spawning, while rainbow trout (including steelhead) continue their life for repeated spawning cycles.
- Exception: Atlantic salmon do not die after spawning. Like steelhead, they continue migrating between fresh and saltwater for repeated reproduction.
Difference #4: Salmon grow to much larger proportions than rainbow trout.
- Exception: Though chinook and Atlantic salmon outmatch steelhead, a large steelhead is comparable to an average salmon.
Salmon and Rainbow Trout Appearance
Aside from size, the general shape of trout and salmon are very similar. This makes identifying the two difficult for those without a keen eye.
Here are some visual details that differentiate trout from salmon.
- Kype: even though inland trout can have a hooked jaw, known as a “kype,” a salmon’s kype is more pronounced.
- Spots: Trout tend to have heavy spotting with black, brown, or orange colors.
- Color: Certain salmon species have vibrant colors, especially pink. This is due to their high crustacean and shrimp diets and is common with coho, pink, and sockeye salmon.
- Shape: You will notice that rainbow trout have blunt noses while salmon have a torpedo shape.
Salmon and Trout Habitat
A common misconception is that all salmon are anadromous and trout are freshwater fish. While this logic applies to most cases, it doesn’t hold up for every species.
All salmon begin and end their life in freshwater. After hatching upriver, they retreat to the ocean to grow rapidly. One to five years later, they return to their birth site to lay or fertilize eggs. After spawning, this anadromous fish dies (except for Atlantic salmon).
Meanwhile, most trout remain in freshwater, but some are ocean-dwellers. A clear example is steelhead trout, that, like salmon, are born in a river and retreat to saltwater. But steelhead are not the only saltwater trout. Cutthroat trout have a sea-run variation known as Coastal cutthroat, which are also anadromous.
So, when describing the difference between trout and salmon, remember: all salmon are sea dwellers, and most trout are freshwater fish.
Types of Salmon
Think of it this way, all salmon and trout fall under the same umbrella, Salmonidae. But there is no neat classification of “trout” and “salmon,” which makes it confusing.
Below, I have categorized salmonids by their genus to comprehend their differences. You will notice two things.
First, some salmon have close genetic ties to some trout. Second, “salmon” and “trout” can be misleading terms, as they are more labels than scientific classifications. Let’s dive in and clarify the Salmonidae family tree.
Common Salmo Fish
The most common salmon species belonging to the Salmo genus is Atlantic salmon. Interestingly, brown trout also belong to the Salmo genus. So, in this case, Atlantic salmon are more closely related to brown trout than Pacific salmon.
Common Oncorhynchus Fish
Common salmon include chinook, sockeye, pink, and chum. People often refer to these as Pacific salmon since they originate from and live in the upper Pacific.
This genus also includes cutthroat and rainbow trout. Again, belonging to the same genus means rainbow trout are more closely related to chinook salmon than brown trout.
What Other Fish Are Salmonids?
The Salmonidae category includes char, whitefish, grayling, taimen, and lenoks. Popular species include arctic grayling, brook, lake, and bull trout. These “trout” are char, reinforcing that the “trout” title is for convenience, not science.
Don’t trust a “trout” label to justify which fish are more related.
Do Salmon and Rainbow Trout Taste The Same?
So now that you know the close relationship between some trout and some salmon, how close is their flavor? Rainbow trout tend to have a less fishy flavor with a nutty taste. Meanwhile, salmon have a bolder fish flavor compared to the mild rainbow trout.
Salmon’s taste can vary depending on cooking methods and the fish’s home. While hatchery salmon and trout have a bland flavor, wild fish have more taste due to their varied diet.
Which Fish Is Healthier To Eat?
To no surprise, even their health effects overlap. Salmon and trout are similar in fat, protein, and omega-3 content. Trout have higher Vitamin D, and salmon contain more Vitamin A. That said, overall, salmon is the healthier option.
Are Rainbow Trout and Salmon High In Mercury?
High mercury levels are a common concern for anyone eating fish. Though you should still be mindful of your intake, salmon and rainbow trout meat have lower mercury concentrations. This is due to their lower status on the food chain.
Whether you’re interested in salmon and rainbow trout for the flavor or the fishing, identifying the two can be confusing. Salmon are anadromous and generally bigger than rainbow trout, but these differences aren’t reliable.
If you happen to be on a game show with money at stake, remember they are different fish that belong to the same family, Salmonidae. From there, identifying the two requires a taxonomy degree or time on the water.
My recommendation? Save some tuition, and choose time on the water instead!