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Safety concerns with consuming fish

Cooked salmon on plate.

Grilled salmon, broiled walleye, fresh caught sunfish or a tasty cold tuna sandwich on toast, sound good? There are plenty of good reasons to eat fish: It’s high in protein, low in fat, an excellent source of B-complex vitamins and trace minerals, and rich in healthful omega-3 fatty acids.

But there are safety concerns that may make you think twice about eating fish.

  • Is my fish contaminated with pollutants?

  • What kind of fish (and how much) is safest for my family to eat?

  • Is the “fresh fish” I buy really fresh?

Contaminants in fish

As part of a low-fat, heart-healthy diet, consumers are hearing the message to incorporate more fish in their diets. Yet, reports question the safety of eating fish because of unacceptable levels of PCBs and the most toxic form of mercury, methyl mercury that builds up in fish tissue.

PCBs and mercury are industrial pollutants that find their way into fresh waters and oceans where they are absorbed by fish. Large predator fish at the top of the food chain, such as shark, swordfish and king mackerel, accumulate the most contaminants. These chemicals build up in fish and people over the course of a lifetime.

Why are mercury and PCBs dangerous?

  • Mercury can damage your nervous system and kidneys if it builds up in your body.

  • Symptoms of mercury poisoning: tingling, prickling or numbness in hands and feet or changes in vision. The body can eliminate mercury eventually and many of the adverse effects can be reversed.

  • Young children, developing fetuses and breast-fed babies are at most risk. Small amounts of mercury can damage a brain that is just starting to form or grow.

  • Too much mercury may affect a child’s behavior and lead to learning problems later in life.

  • Babies exposed to PCBs during pregnancy may have lower birth weight, reduced head size and delayed physical development.

Pollutants in fresh-caught fish

Teenager holds up bass.

In Minnesota, mercury, PCBs and dioxin often pollute lakes and rivers. You can’t see, smell or taste mercury or PCBs in fish.

For safer fresh caught fish:

  • Release large fish and keep smaller fish. They are safer and taste better.

  • Perch and crappies are safer than walleye or northern pike.

See information on how much fish you can eat from your lake or river or contact the Minnesota Department of Health at 800-657-3908.

Concerns with PCBs in farm-raised salmon

A study made headlines when it reported unacceptable levels of PCBs in fish feed given to farmed salmon. The study said that PCB levels in farmed salmon, especially those from Europe, were about seven times higher than in wild salmon. Yet, there is no official agreement that the amount of PCB’s in farmed fish poses a health hazard. Until more research results are available, it is reasonable to eat farmed salmon less frequently and eat wild salmon more often.

In the United States, most consumed farmed salmon comes from Chile (56 percent), Canada (31 percent) and the U.S. (6 percent). Farm fish can continue to be part of a healthy diet but researchers suggest consumers eat no more than two meals of farmed salmon per week.

When choosing salmon:

  • Packaged salmon. Check for country of origin labeling for farmed salmon. Choose fish from North or South American water.

  • Fresh salmon. Ask for the country of origin.

  • Canned salmon is often harvested in the wild.

Concerns with mercury in tuna

The Federal Fish Advisory includes albacore tuna and tuna steaks in the list of fish with high levels of mercury. Research found “white” canned, albacore tuna has three times the mercury levels as the “light” tuna. As a result of these findings, Minnesota Department of Health advises one meal per week of canned “light” and one meal per month for canned “white” tuna.

Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, pollock and catfish.

Safety guidelines for minimizing contaminants

For most people, 2 meals of fish per week is generally considered optimal for balancing the health benefits and the health risk from contaminants in fish. But for women of child-bearing age and children age 15 or under, the guidelines are stricter.

Choosing which fish to eat for those meals is important to minimize exposure to mercury and other chemicals in fish.

Sensitive Population: Guidelines for pregnant women, women who could become pregnant and children under 15 years of age

Type of fish How often can you eat it?
Purchased catfish (farm-raised), cod, herring, Atlantic mackerel, pollock,
salmon (farm raised or wild, Pacific and Atlantic not Great Lakes),
sardines, shellfish (crab, oysters, scallops, shrimp), tilapia, fish sticks and sandwiches
2 servings per week
Canned “light” tuna, halibut; Minnesota caught: sunfish, crappie,
yellow perch, bullhead, lake whitefish, lake herring
1 serving per week
Canned albacore tuna, Chilean seabass, grouper, marlin,
tuna steak or fillet; Minnesota caught: bass, catfish, walleye,
northern pike, lake trout, other Minnesota species
1 serving per month
Shark, swordfish, tilefish, king mackerel;
Minnesota caught muskellunge
Do not eat

Source: Minnesota Department of Health website. Safe Eating Guidelines.

General Population: Guidelines for boys age 15 and over, men, and women not planning to become pregnant

Type of fish How often can you eat it?
Minnesota caught trout, lake herring, lake whitefish, sunfish, crappie, yellow perch or bullhead Unlimited amounts
Minnesota caught bass, catfish, northern pike, walleye and other Minnesota species 1 serving per week
Purchased shark, swordfish, tilefish, king mackerel 1 serving per month

Source: Minnesota Department of Health website. Safe Eating Guidelines.


Suzanne Driessen, Extension educator; Deb Botzek-Linn, former Extension educator;  William Schafer, emeritus Extension specialist; Craig Hassel, Extension Nutritionist; and Jeff Gunderson, former Sea Grant Extension liaison

Reviewed in 2020

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