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Fish and Mercury

The levels of mercury found in fresh water fish from Ontario lakes can vary. The Guide to Eating Ontario Fish includes everything you need to know about the safety of eating Ontario sport fish. Check it out online or get a copy from your local public health unit or the Ministry of the Environment and Climate Change.

Is fish a healthy food choice?

Yes! Eating Well with Canada’s Food Guide recommends at least two food guide servings of fish a week. One serving is 75 grams, which is 2 ½ oz or ½ cup. When cooked, one serving of fish should be about the size of a deck of cards. Fish contains protein, vitamin D and iron. Certain fish also have omega-3 fats that have heart health benefits.

What types of fish are safe to eat?

There are many safe and healthy fish to eat. However, some fish have higher levels of mercury, a toxin that can be harmful to humans. Because mercury affects the developing brain, it’s especially important for women that may become pregnant, are pregnant or nursing, as well as young children to limit their exposure to mercury in fish.

Choose most often: low mercury fish that is high in omega-3 fats.

  • Salmon, anchovy, char, herring, Atlantic mackerel, pollock (Boston bluefish), smelt, rainbow trout, lake whitefish, shrimp, clam, mussel, and oyster.
  • Cod, haddock, halibut, sole, scallops and squid, snapper, perch, bass and tilapia.
  • Choose “light” tuna. Look for skipjack or tongol on the label. It has less mercury than “white” (albacore) tuna and is generally less expensive.
Limit you intake of larger fish species such as tuna, shark, swordfish, marlin, orange roughy, and escolar as these fish tend to accumulate more mercury over time. If you enjoy these larger fish, eat no more than the amounts shown below and make up the rest of your weekly fish servings from other low mercury fish.

Recommended mercury limits
The table below summarized Health Canada’s recommended mercury limits for various populations. The recommended limits should not be exceeded.

Population​ Recommended limit​
​General Population ​150 g per week
Women who are or may become pregnant and nursing moms​ ​150 g per month
Women who are pregnant or nursing ​150 g per month
Children 1-4 years old​ ​75 g per month
Children 5-11 years old​ ​125 g per month
For more information on fish, mercury and/or safe fish consumption go to Health Canada or Eat Right Ontario and search for Mercury in Fish.