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

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.

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.

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.