Trout and salmon are nutritionally close enough that neither is a clear winner across the board. Salmon delivers more omega-3 fatty acids, while trout is leaner, higher in vitamin D, and lower in mercury. The “healthier” choice depends on what you’re optimizing for.
Protein and Fat: A Side-by-Side Look
Per 100 grams of farmed fish, Atlantic salmon provides 20.4g of protein compared to rainbow trout’s 19.9g. That half-gram difference is negligible. Where the two diverge is fat content: farmed Atlantic salmon contains 13.4g of fat per 100g, while farmed rainbow trout has just 6.18g. That makes trout roughly half the fat of salmon, which matters if you’re watching overall calorie intake.
Cholesterol is similarly close. Salmon has about 63mg per 100g, and trout has 70mg. Neither amount is high enough to be a concern for most people. Potassium, important for blood pressure regulation, is nearly identical: 384mg in salmon versus 377mg in trout.
Omega-3s: Salmon’s Biggest Advantage
The main reason salmon has its reputation as a superfood is its omega-3 content, specifically EPA and DHA, the two forms your body uses most readily to reduce inflammation and support heart and brain health. Farmed Atlantic salmon contains about 0.6g of EPA and 1.2g of DHA per 100g of fish. Rainbow trout (steelhead) has considerably less: 0.1g of EPA and 0.4g of DHA per 100g.
That’s a significant gap. A single serving of Atlantic salmon gives you roughly 1.8g of combined EPA and DHA, while rainbow trout delivers about 0.5g. If your primary goal is maximizing omega-3 intake, salmon is the better pick by a wide margin. Lake trout narrows this gap considerably, with up to 0.5g of EPA and 1.1g of DHA, but lake trout is less commonly available than rainbow trout.
Wild salmon species fall between the two. Sockeye delivers about 1.2g combined, chinook about 1.4g, and pink salmon about 1.0g per 100g serving.
Vitamin D and Other Micronutrients
This is where trout pulls ahead. A three-ounce serving of rainbow trout provides about 645 IU of vitamin D, covering more than 100% of the daily value in a single serving. The same portion of salmon delivers roughly 375 IU. Both are excellent sources, but trout gives you nearly twice as much, which is notable given that vitamin D deficiency is common and difficult to get from food alone.
Rainbow trout also provides about 4 micrograms of vitamin B12 and 24 micrograms of selenium per three-ounce serving. B12 is essential for nerve function and red blood cell production, and selenium acts as an antioxidant that supports thyroid health. Salmon contains both nutrients too, but trout’s vitamin D advantage is its clearest nutritional edge.
Mercury and Contaminants
Both fish are low in mercury, but salmon is the cleaner option. According to FDA testing data, fresh or frozen salmon averages 0.022 parts per million of mercury, while freshwater trout averages 0.071 ppm. Canned salmon is even lower at 0.014 ppm. For context, the FDA considers fish with mercury below 0.1 ppm to be among the lowest-mercury options available, so both trout and salmon fall comfortably in the safe range. You can eat either one two to three times per week without concern, including during pregnancy.
Antioxidant Differences
Both salmon and trout contain astaxanthin, the pigment responsible for their pink-to-orange flesh color. This compound acts as a potent antioxidant. Interestingly, rainbow trout absorbs and retains dietary pigments far more efficiently than Atlantic salmon. Research from ScienceDirect found that trout had a digestibility rate of 96% for astaxanthin compared to just 28 to 31% in salmon, with pigment retention roughly double in trout. The practical significance of this for human health is harder to pin down, since astaxanthin concentrations in the final fillet depend on what the fish was fed. But if you’re eating fish partly for antioxidant benefits, trout’s biology works in its favor.
Sustainability Considerations
Health isn’t only about nutrients. Where and how your fish was raised affects both environmental impact and the quality of what ends up on your plate. Seafood Watch rates Atlantic salmon farmed in Maine or the Faroe Islands as a “Best Choice,” along with ASC-certified sources. However, Atlantic salmon farmed in Canada, Chile, Norway, or Scotland generally falls into “Avoid” territory unless it comes from specific certified or regionally approved operations.
Rainbow trout farmed in the U.S. typically scores well on sustainability ratings. Wild-caught trout can be more complicated, as some steelhead (ocean-going rainbow trout) populations are at risk. When buying either fish, looking for country of origin and certification labels gives you the best signal of both environmental responsibility and farming practices that affect nutrient quality.
Which One Should You Choose?
If you want the most omega-3s per serving, choose salmon. Farmed Atlantic salmon delivers roughly three times the EPA and DHA of rainbow trout, making it the stronger choice for heart health and inflammation. If you’re looking for a leaner fish with exceptional vitamin D content and slightly fewer calories, trout is the better option. It’s also a solid pick if you prefer a milder flavor, since trout is generally less “fishy” than salmon.
For mercury, both are among the safest fish you can eat, though salmon edges out trout slightly. And if cost is a factor, rainbow trout is often cheaper than salmon at the grocery store, making it easier to eat fish regularly, which matters more than which species you pick. Eating either fish twice a week puts you well ahead of the average American’s seafood intake and delivers meaningful benefits for your heart, brain, and overall nutrition.