Swordfish: Nutrition, Mercury and Is It Healthy?

Swordfish is a large, fast ocean predator with a long, flat bill, sold mostly as thick, meaty steaks that hold up well on the grill. In USDA data, cooked swordfish is a lean protein that supplies more than the full Daily Value for selenium and most of the Daily Value for vitamin D in a typical portion. Swordfish mercury is the catch: the FDA and EPA fish advice puts swordfish in its Choices to Avoid group, labeled highest mercury levels, for people who might become or are pregnant or breastfeeding and for children ages 1 to 11. So is swordfish healthy? It depends a great deal on who is eating it. This guide covers swordfish nutrition, the mercury data, who the advice is aimed at, and lower-mercury fish to consider.

Peptide Labs does not sell swordfish or swordfish products. This article is general nutrition information, not medical advice.

What is swordfish?

Swordfish (Xiphias gladius) is a billfish found in tropical and temperate oceans worldwide. NOAA Fisheries describes US wild-caught North Atlantic swordfish as a smart seafood choice because it is sustainably managed and responsibly harvested under US regulations, and its 2022 stock assessment found the stock not overfished and not subject to overfishing. Fishers mainly use pelagic longlines, with rod-and-reel, harpoon and buoy gear as well. Sustainability and mercury are separate questions, though: a well-managed fish can still be high in mercury.

In the kitchen, swordfish is usually cut into steaks, grilled, broiled or seared, and cooked through until the flesh turns opaque. Its firm texture is why it is often compared with tuna steaks rather than flaky white fish.

Swordfish nutrition

The table compares cooked swordfish with cooked Atlantic herring, a lowest-mercury oily fish, per 85 grams (about 3 ounces), using USDA FoodData Central SR Legacy values and FDA Daily Values.

On paper, swordfish nutrition looks strong. Per USDA, a cooked portion carries about as much protein as herring with less fat, more than a full day’s selenium Daily Value, and about 70% of the vitamin D Daily Value. Our vitamin D foods guide and selenium guide put those numbers in context. Swordfish has less than half the EPA and DHA of herring, though, and far less vitamin B12. For more on those marine fats, see our omega-3 guide.

Swordfish mercury: what the FDA data shows

Mercury is where swordfish parts ways with most fish. The FDA and EPA advice about eating fish, revised in October 2021, sorts commonly eaten fish into three groups. Swordfish is in the Choices to Avoid group, labeled highest mercury levels, together with king mackerel, marlin, orange roughy, shark, tilefish from the Gulf of Mexico and bigeye tuna. That advice is written for people who might become or are pregnant or breastfeeding and for children ages 1 to 11.

The FDA monitoring table of mercury in commercial fish shows why. Across 636 swordfish samples tested from 1990 to 2010, the mean was 0.995 parts per million, with a maximum of 3.22. Herring averaged 0.078 parts per million, sardines 0.013 and fresh or frozen salmon 0.022 in the same table. CDC’s guidance for pregnant women also names swordfish, with shark, king mackerel and tilefish, among high-mercury fish to avoid.

These are averages, and averages hide variation. In the same FDA table, individual swordfish samples ranged up to 3.22 parts per million, while the highest herring sample was 0.56. The data come from FDA testing spread over many years, so any single fish may sit above or below the mean. What the table shows clearly is the gap between groups: swordfish averages more than ten times the mercury of herring and many times that of salmon or sardines.

Is swordfish healthy for you?

There are two honest answers. For people who are pregnant, breastfeeding or might become pregnant, and for young children, the official US answer is to choose other fish: swordfish sits in the group the FDA and EPA say to avoid. For other adults, that chart is not aimed at them directly, and swordfish does bring lean protein, selenium and vitamin D, so the choice is more personal. Many people simply pick lower-mercury fish for most meals. If fish is a big part of your diet, or you have questions about mercury and your health, a clinician or registered dietitian is the right person to ask.

If you like firm, meaty fish but want lower mercury, the FDA lowest-mercury group includes options such as herring, sardines, anchovies, salmon and Atlantic mackerel. Note that king mackerel is in the same avoid group as swordfish; our mackerel guide explains the difference. Milder white fish such as tilapia and trout are other common swaps, and our pescatarian diet guide covers building meals around seafood.

Cooking swordfish and food safety

• Cook it through: CDC advises cooking seafood to an internal temperature of at least 145 degrees Fahrenheit. Raw fish dishes such as crudo carry a parasite risk; CDC lists raw or undercooked fish as the cause of anisakiasis.
• Pregnancy: CDC advises pregnant women to avoid raw or undercooked fish as well as high-mercury fish, so swordfish in any form is on the avoid side of that list.
• Allergy: fish is one of the nine major food allergens under US law, so packaged foods must declare it.
• Keep it cold: choose swordfish from a refrigerated case or frozen, and keep it chilled until cooking; this is plain kitchen practice for all fresh fish.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Food comes first; follow the label and ask a healthcare provider before starting a supplement, especially if you take medicines, are pregnant or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

Related guides: Herring: Nutrition, Mercury, Pickled Herring and Safety, Tuna: Canned Tuna Nutrition, Mercury and Types Explained, Salmon: Nutrition, Benefits and Wild vs Farmed Salmon.