Most chefs cook swordfish to at least 130°F, since the safety margin between rare and risky is far narrower than with tuna or salmon. The dense muscle hides parasites, histamine can build during storage, and a rare center carries real consequences ranging from short-term food poisoning to long-term mercury accumulation.
Below, you’ll find how swordfish compares with other fish, the specific parasite and histamine risks tied to rare preparation, and the temperatures that actually make it safe at home.
Why Swordfish Lives in a Safety Gray Zone
Swordfish is a large, fast pelagic predator built like a torpedo, and its muscle is dense enough that a pink center can look perfectly cooked to anyone used to searing tuna. The texture reinforces the illusion. A thick swordfish steak holds together on the fork the way a well-rendered piece of beef would, which makes translucent flesh feel like a deliberate choice rather than a warning sign.
Unlike bluefin tuna or farmed yellowtail, swordfish is rarely graded or labeled “sashimi-grade” in the US market. The voluntary sashimi-grade labeling system that exists for some species was not designed with swordfish in mind, and most retailers who carry swordfish treat it as a cooking fish from the moment it arrives. That means even high-quality sushi suppliers often sell swordfish for cooked preparations only, so any raw or rare service at home starts from a less controlled baseline than tuna would.
The Anatomy of a Risky Center
Visual doneness cues break down completely with swordfish because the muscle is so tightly packed. A center that looks rosy and slightly translucent in tuna means the same parasite load as a center that looks identical in swordfish, but the industry expectation for those two species differs sharply. Tuna is handled and frozen specifically to be served rare; swordfish is not, and that gap is where most of the safety questions live.
The Specific Risks of Undercooked Swordfish
Three distinct food safety problems attach themselves to rare swordfish, and they behave differently enough that you need to understand each one. Parasites lead the concern, histamine toxicity is the silent threat tied to storage, and bacterial contamination plays a smaller but real supporting role.
Parasites: Anisakis and Similar Worm Larvae
Saltwater fish carry Anisakis larvae as a normal part of their life cycle, and swordfish is no exception. These worms are killed by sufficient heat or by sustained cold, but a rare center leaves them viable. Eating live Anisakis larvae causes abdominal cramps and sometimes nausea within hours of the meal, and in stubborn cases the larvae have to be removed endoscopically. The CDC tracks these cases every year, and improperly frozen or undercooked marine fish is the consistent source.
Histamine and Scombroid Poisoning
Belonging to the scombroid family alongside tuna and mackerel, swordfish carries identical histamine risks when temperature control lapses between the boat and the kitchen. Bacteria on the fish convert natural histidine into histamine once the surface warms above refrigeration, and that histamine survives cooking. Flushing, headache, rash, and a metallic peppery taste in the bite are the giveaway signs, and they show up within an hour of the meal rather than the next morning.
Bacteria and Cross-Contamination
Surface bacteria like Vibrio species draw less attention than parasites, but they still matter for any raw preparation. Cold handling from the store to your pan keeps the risk low, and a hot sear on the outside reduces it further. The center is where problems concentrate when swordfish is served rare, so the cooking method matters as much as the final temperature.
Mercury and Long-Term Exposure Concerns
Swordfish has one of the highest methylmercury concentrations of any commonly eaten fish, and the FDA’s seafood advisory places it in the top tier alongside king mackerel, tilefish, and bigeye tuna. A single 6-ounce serving can deliver more mercury than most adults should eat in a week, which is why the Environmental Defense Fund seafood selector and the Monterey Bay Aquarium Seafood Watch both flag it as a “choose less” or “avoid” option for routine meals.
Cooking does not remove mercury. Whether you sear the steak, smoke it, or serve it sashimi-style, the mercury stays in the flesh. That detail matters because the mercury question is sometimes folded into the undercooked conversation by mistake, as if cooking would fix it. Heat only addresses parasites and bacteria, leaving the heavy-metal exposure unchanged regardless of doneness.
Who Needs to Be Most Careful
Pregnant women, people trying to conceive, nursing parents, and young children are advised to skip swordfish entirely. The FDA’s 2017 advice and its current guidance both recommend lower-mercury alternatives like salmon, sardines, and anchovies for those groups. For healthy adults, the advice is rotation rather than prohibition: an occasional swordfish meal fits inside the weekly mercury budget, but a regular weekly habit accumulates quickly into a range worth monitoring with a clinician if you eat a lot of predatory fish.
Temperatures, Freezing, and What Actually Makes Swordfish Safe
The numbers below are the standards that food safety agencies publish, and they are the only ones worth treating as a real guideline rather than a chef’s guess.
| Safety Method | Threshold | What It Kills |
|---|---|---|
| USDA-recommended cooking temperature | 145°F (63°C) internal | Parasites and most bacteria |
| Sushi-grade freezing (FDA standard) | -4°F (-20°C) for 7 days, or -31°F (-35°C) for 15 hours | Parasites |
| Minimum medium-rare pull temperature | 130°F (54°C) at the center | Some parasite risk remains |
| Cold-smoking safety baseline | 145°F internal before smoking | Parasites and bacteria |
The 145°F USDA figure is the conservative line, and it eliminates parasites with a comfortable margin. The 130°F medium-rare pull is what some chefs use as a calculated compromise, and it works only when the fish has first been frozen to the FDA’s parasite-destruction standard. Without that prior freeze, a 130°F center is not a guarantee.
Why Visual Cues Fail With Swordfish
A translucent pink center tells you nothing safe about swordfish. The muscle is so dense that even fully cooked swordfish can look slightly pink at the center, and a rare steak can look cooked all the way through to an untrained eyes. An instant-read thermometer is the only reliable check, and probing at the thickest point of the steak gives you the number that actually matters.
How Swordfish Compares With Tuna, Salmon, and Other Fish
Swordfish is often grouped mentally with tuna because they share the open-ocean lifestyle, but the safety profiles diverge sharply once you start serving either one rare.
| Fish | Typical Raw or Rare Service? | Parasite Risk | Mercury Level |
|---|---|---|---|
| Swordfish | Uncommon, not sashimi-graded | Moderate to high | High |
| Bluefin or yellowfin tuna | Common, often flash-frozen for sushi | Lower in deep-ocean species | Moderate to high (varies by species) |
| Wild Pacific salmon | Common after commercial flash-freezing | Moderate, neutralized by freezing | Low |
| Farmed Atlantic salmon | Often served raw or cured | Low in controlled aquaculture | Low |
| Marlin | Rare in the US, similar to swordfish | Moderate | High |
Tuna gets a pass for rare service largely because deep-ocean species carry fewer parasites than coastal or bottom-dwelling fish, and the commercial sushi supply chain freezes tuna routinely as a quality step that also happens to neutralize parasites. Swordfish shares tuna’s open-ocean habitat but lacks that standardized raw-supply pipeline, so the same general trust does not transfer.
When Swordfish Makes Sense Versus Other Choices
For a hot summer grill where the plan is a fully seared steak, swordfish earns its place as a sturdy, meaty option with a flavor that holds its own against bold rubs. For a raw or rare application, salmon or farmed tuna are safer starting points with clearer supply chains behind them. Choosing farmed salmon over swordfish for a ceviche or crudo is one of the easiest risk reductions available, and it cuts the mercury exposure to a small fraction of what swordfish would deliver.
Safer Ways to Serve Swordfish at Home
If you still want to bring swordfish to the table, the goal is to control every variable you can actually control at home: temperature, source, and frequency.
- Use an instant-read thermometer: Probe the thickest part of the steak and aim for at least 145°F for full safety, or 130°F only if the fish was previously frozen to FDA parasite-killing standards.
- Pat the steak dry before seasoning: Surface moisture delays browning and forces a longer sear that can dry out the edges before the center reaches temperature.
- Sear hot and fast over high heat: A screaming-hot cast iron or grill grate gives you the Maillard crust without extended cooking time that can toughen the meat.
- Rest the steak for 3–5 minutes: Carryover heat pushes the internal temperature up several degrees during the rest, so pulling early lets you hit the target without overshooting.
- Limit swordfish to occasional meals: Once every two to three weeks keeps most adults inside the EPA mercury reference dose, with smaller portions for lighter body weight.
- Buy from a trusted fishmonger: Ask when the fish arrived and how it has been stored. Swordfish that has been sitting on ice for several days is a poorer candidate for any rare treatment than a same-day cut.
A 1-inch swordfish steak pulled at 130°F and rested under foil will land close to 135°F at the plate, which still sits inside the parasite-risk zone unless the fish was previously frozen to spec.
The Mercury Trade-Off Most Recipes Skip
Most swordfish recipes focus on flavor and technique and leave mercury out of the conversation entirely. That omission matters because swordfish is one of the few fish where a single generous serving can move the needle on weekly mercury intake, even for adults without heightened sensitivity. Treating swordfish the way you’d treat a rich cut of beef, as something portioned and paced rather than piled high, is the simplest way to enjoy the flavor without letting the cumulative exposure drift upward unnoticed.
Pinning down temperature and freezing rules is useful, yet taste still matters, so the final step is shaping a kitchen habit that actually holds.
Bottom Line
Swordfish can be eaten undercooked, but the safety case is weaker than for tuna or salmon and the mercury cost is real. Cook it to at least 145°F if you want certainty, freeze it to FDA specs first if you want a 130°F medium-rare pull, and keep the servings occasional rather than routine.
FAQ
Can you eat swordfish medium rare?
Some restaurants serve swordfish at roughly 130°F for a medium-rare result, though residual parasites remain a concern unless the fish was first held at -4°F for seven days or -31°F for fifteen hours.
What is the safe internal temperature for cooked swordfish?
The USDA recommends 145°F (63°C) at the thickest part of the steak for full parasite and bacterial safety, measured with an instant-read thermometer.
Does swordfish have parasites like salmon?
Yes. Swordfish can carry Anisakis larvae like other saltwater fish, and these parasites survive in undercooked flesh unless the fish is cooked to 145°F or frozen to FDA parasite-destruction standards.
Is swordfish high in mercury and should it be avoided?
Swordfish is one of the highest-mercury fish commonly sold in the US, and the FDA advises pregnant women, young children, and people trying to conceive to avoid it. Healthy adults should limit swordfish to occasional servings rather than weekly meals.
Is it ok to eat pink swordfish?
Pink coloring alone does not confirm safety. Swordfish muscle stays dense enough that even fully cooked flesh can look pink, and a rare steak can look opaque, so an instant-read thermometer is the only reliable check.
What happens if swordfish is undercooked?
Raw or rare swordfish may pass live Anisakis parasites to the diner, and improperly stored fillets can trigger scombroid poisoning or, in rare cases, bacterial infection. Symptoms range from abdominal pain and nausea within hours to flushing and headache from histamine toxicity.
