Salmon vs Tuna: Which Fish Wins?

The Case for Fatty Fish

Salmon and tuna are consistently ranked among the most nutritious proteins available. Both are rich in high-quality protein and provide significant amounts of omega-3 fatty acids, B vitamins, selenium, and iodine. Health authorities including the American Heart Association recommend eating fatty fish at least twice per week — and both salmon and tuna qualify as excellent choices for meeting this guidance.

Yet they are nutritionally distinct in important ways. Understanding the differences helps consumers make informed decisions based on their specific dietary goals, budget, and health priorities.

Nutritional Comparison: Fresh/Cooked (per 100 g)

Omega-3 Fatty Acids: Salmon's Major Advantage

Salmon's defining nutritional superiority is its exceptional omega-3 content. Farmed Atlantic salmon provides approximately 2,260 mg of EPA + DHA per 100 g — more than eleven times the amount in an equivalent serving of yellowfin tuna (200 mg). Even wild-caught salmon (typically 1,200–2,000 mg EPA+DHA per 100 g) handily outpaces tuna.

The American Heart Association recommends 500 mg EPA+DHA per day for cardiovascular health, and up to 1,000 mg for people with documented coronary artery disease. A single 100 g serving of salmon exceeds both thresholds; tuna does not. For people who eat fish primarily for omega-3 intake, salmon is dramatically more effective per serving.

The reason tuna is low in omega-3s despite being a fatty fish relates to tuna's migratory lifestyle — they burn through their stored fat reserves during long ocean crossings, resulting in leaner flesh at time of catch compared to salmon.

Mercury: Tuna's Limitation

Mercury bioaccumulates in marine food chains through a process called biomagnification. Larger, longer-lived fish that consume many smaller fish accumulate mercury in their tissues over their lifespan. Tuna — which can live 40+ years and reaches large sizes — accumulates substantially more mercury than salmon.

The FDA/EPA joint advisory classifies fish into three tiers for mercury:

• Best choices (eat 2–3 servings per week): salmon, light canned tuna, sardines, trout
• Good choices (eat 1 serving per week): albacore/white canned tuna, yellowfin tuna, mahi-mahi
• Choices to avoid (especially for pregnant women and young children): bigeye tuna, shark, swordfish, king mackerel

Light canned tuna (made primarily from skipjack tuna) contains roughly 17 µg mercury/100 g. Albacore/white canned tuna contains ~40 µg/100 g. Salmon typically contains about 3 µg/100 g — one of the lowest mercury levels among fish commonly consumed in the US.

For pregnant women, nursing mothers, and young children, salmon is significantly safer for regular consumption. The FDA's recommendation of up to 3 servings per week applies to salmon with no caveats; light tuna is limited to 2 servings per week for this population.

Vitamin D: The Salmon Standout

Salmon is one of the very few significant dietary sources of vitamin D. A 100 g serving of farmed Atlantic salmon provides approximately 97% of the Daily Value for vitamin D (526 IU). Wild-caught salmon can be even higher (600–1,000 IU per 100 g depending on season and habitat). Tuna contains only trace amounts.

Vitamin D deficiency is widespread — estimated to affect 40% of the US adult population and higher percentages in northern latitudes and populations with limited sun exposure. For people with insufficient sun exposure, salmon represents one of the most potent dietary strategies for improving vitamin D status. Supplementation remains effective, but food-form vitamin D comes packaged with a full complement of co-nutrients absent from supplements.

Farmed vs. Wild Salmon

This distinction matters nutritionally. Farmed Atlantic salmon has higher omega-3 content than most wild Pacific salmon because farmed fish are fed omega-3-rich feeds and have limited opportunity to burn their fat reserves. However, farmed salmon also has a higher total fat content overall, including more omega-6 fatty acids (from plant-based feed ingredients), and potentially higher levels of persistent organic pollutants (POPs) that concentrate in fat — though modern aquaculture standards have significantly reduced POP levels compared to 20 years ago.

Wild salmon (sockeye, coho, king/chinook, pink, chum) have leaner, firmer flesh with 1,200–2,500 mg EPA+DHA per 100 g depending on species. Sockeye and king are fattiest; pink and chum are leaner. Both farmed and wild salmon are nutritionally excellent choices far superior to most other widely available proteins.

Cost, Convenience, and Practical Use

• Budget: Canned light tuna is among the most affordable protein sources globally — typically $1–2 per can (3 oz / 85 g) in the US. Canned salmon is pricier but still inexpensive relative to fresh. Fresh salmon costs $15–30/kg in most markets.
• Shelf life: Canned tuna and salmon last 3–5 years unopened. Fresh fish must be used within 1–2 days of purchase.
• Culinary versatility: Tuna (canned) integrates easily into salads, sandwiches, and pasta. Salmon's higher fat content makes it more forgiving to cook — it stays moist at higher temperatures and works well baked, grilled, poached, or pan-seared.
• Optimal choice by goal: For maximum omega-3 intake and vitamin D → salmon. For maximum protein per calorie with lowest mercury → light canned tuna or fresh yellowfin. For best cost-to-nutrition ratio → canned light tuna (protein and selenium) or canned pink salmon (omega-3s).