How to Prevent Food Poisoning From Fish and Shellfish—and Other Safe Seafood Tips

Article By Sharon Liao Published July 11, 2025
Article Source: https://www.consumerreports.org/health/food-safety/prevent-food-poisoning-from-fish-shellfish-a9520364050/

Confused about which fish are okay to eat and which to avoid? Here's the lowdown.

Seafood may lead to a longer, healthier life, thanks to its rich combination of nutrients. "The zinc, vitamin B12, and omega-3 fats in fish and shellfish reduce inflammation and promote healthy aging," says Dolores Woods, RDN, a nutritionist supervisor for the Nourish Program at UTHealth Houston School of Public Health.

Experts recommend two servings of fish per week (a total of 8 ounces), but even less can be beneficial. A 2023 study in the Journal of Translational Medicine found that people who ate one serving of fatty fish per week (such as salmon or sardines) were 7 percent less likely to die during the 15-year follow-up than those who ate none.

There are downsides to seafood, though. It spoils quickly and can contain bacteria, viruses, pollutants, or parasites. Cooking reduces the risks, but it’s not foolproof. "Older adults and those with compromised immune systems are more susceptible to getting sick," Woods says. Use this advice to reel in the benefits of seafood—without any catches.

Shopping for Seafood

Choose smaller fish. Large fish, like swordfish and bluefin tuna, tend to have higher mercury and contaminant levels than smaller ones because they’re higher up in the food chain. Salmon, haddock, and tilapia are exceptions; they’re larger, but low in mercury. Also consider herring, anchovies, and sardines.

Opt for frozen. "Frozen fish is processed and flash-frozen within a few hours or days to preserve its quality," says Brandii O’Reagan, a fisheries specialist at Washington Sea Grant at the University of Washington. "Compare that to fresh-caught fish, which can take up to a week to get processed and shipped to grocery stores." Plus, the commercial process for freezing fish kills potentially harmful parasites. Cooking destroys most of the parasites, but freezing is important if you’re eating the fish raw or undercooked.

Ask about the shellfish harvest. Clams, mussels, and oysters filter-feed—that is, they get their food by pumping water through their bodies—making them susceptible to contaminants in the water. To check that shellfish comes from safe waters, look for tags with a processor’s certification number detailing where and when it was harvested, O’Reagan says. This ensures that it meets national shellfish safety standards. For unpackaged shellfish, ask your fishmonger.

Check for freshness. "Trust your nose," O’Reagan says. Fresh seafood should smell mildly of the ocean, not strongly of fish or ammonia. Look for firm, springy flesh and clear, bright eyes if you’re buying a whole fish. Frozen seafood shouldn’t have any frost or ice crystals, and it should be frozen solid. Buying shellfish? Opt for live or frozen. Live clams, mussels, and oysters should close when tapped; lobsters and crabs should have some leg movement.

Prepping and Cooking Tips

Keep fish chilled. Salmonella and other bacteria can double in number every 20 minutes between 40° F and 140° F, according to the Department of Agriculture. So store seafood in the fridge or on ice within 2 hours of purchasing it (1 hour if it’s 90° F or warmer outside), says Michael Ciaramella, PhD, a seafood safety and technology specialist at New York Sea Grant, a program of the State University of New York and Cornell University. Not only can bacteria make you sick but they also create chemicals called histamines in some fish, such as mahi-mahi and tuna. This can lead to scombroid poisoning, or histamine poisoning, which can cause a rash, diarrhea, and vomiting.

Defrost in the fridge. You want frozen fish to stay cold as it thaws to prevent the surface from reaching 40° F, the temperature at which any bacteria present before freezing begin to grow.

Use fish quickly. Eat fresh or defrosted seafood within a day or two. You can freeze fresh-caught fish within that time frame, but toss previously frozen items. It’s not a safety issue; fish doesn’t refreeze well, Woods says.

Cook it safely. Use an instant-read food thermometer to make sure that seafood reaches an internal temperature of 145° F, which kills bacteria. "The fish should flake away easily," Woods says. Clams, mussels, and oysters open when they’re done; toss any that stay closed. Cook shrimp, crab, and lobster until they turn opaque and pearly, and scallops until they’re milky white and firm.

Consider canned. The fish is heated during the canning process, so bacterial contamination isn’t a big concern. Plus, canned salmon, sardines, and tuna are convenient and can be as good for you as fresh. With tuna, choose light or skipjack varieties over albacore most of the time because they have lower mercury levels.

Ordering Seafood in Restaurants

Research restaurants. It’s always a smart idea to check an establishment’s health inspection score on your local health department’s website. Also read reviews, and look for restaurants without complaints about cleanliness or food poisoning, Woods says.

Select safer sushi. Sushi made with raw fish and sashimi is a risky choice. And some options, such as maguro, meji, and toro, are made from bigeye or bluefin tuna, which can be high in mercury. Instead, order sushi made with vegetables, eggs, or cooked seafood. "California rolls are a good pick because the imitation crab is cooked," Woods says. Tempura, unagi (eel), tamago (egg omelet), ebi (cooked shrimp), and baked scallop rolls or sushi are other safer options.

Order fish well done. Some restaurants serve seared tuna, which can be raw on the inside, or medium-cooked salmon. Also, steer clear of ceviche, poke, and cold-smoked fish. These dishes are "cooked" with salt, sauces, or citrus instead of heat.

Skip raw shellfish. Raw oysters and clams can harbor vibrio or other bacteria, which can cause stomach cramps, diarrhea, nausea, and fever. (Despite what you may have heard, hot sauce doesn’t kill bacteria.) Order broiled, grilled, or baked shellfish.

Editor’s Note: This article also appeared in the August 2025 issue of Consumer Reports On Health.

TrainCan, Inc. note: Canadian recommended cooking temperature for fish is 70°C/158°F.