Overview

Mercury is a metal found naturally in the air, soil, and water. Fish can take in mercury from water. When you eat fish containing mercury, you can also take in the mercury. The metal builds up in your bloodstream over time. It slowly leaves the body through urine, stool, and breast milk.

For most people, eating a small amount of fish high in mercury isn't a health concern. Fish are part of a healthy diet. But in a fetus or child, too much mercury can harm the brain and nerves.

If you might become pregnant, are pregnant, are breastfeeding, or are the parent or caregiver of a child age 11 or younger, talk to your doctor about which fish are safe for you and your child to eat. If you eat a lot of fish high in mercury, it may take up to a year for your mercury levels to drop.

Choosing fish that is low in mercury

Most people should not eat more than 150 g (5 oz) per week of fish that are known to have higher mercury levels. These include fresh or frozen tuna (not canned "light" tuna), shark, swordfish, marlin, orange roughy, and escolar. Some people need to restrict high-mercury fish even more: ^{footnote 1}

• Nursing mothers or women who are or may become pregnant should limit high mercury fish intake to no more than 150 g (5.3 oz) a month.
• Children 5 to 11 years of age should limit high mercury fish intake to no more than 125 g (4.4 oz) a month.
• Children 1 to 4 years of age should limit high mercury fish intake to no more than 75 g (2.7 oz) a month.

Most Canadians don't need to limit how much canned (white) albacore tuna they eat each week. But women who are or may become pregnant, nursing mothers, and children need to limit canned albacore tuna intake to no more than:

• 300 g (10.6 oz) each week for women who are or may become pregnant, or who are nursing.
• 150 g (5.3 oz) each week for children 5 to 11 years of age.
• 75 g (2.7 oz) each week for children 1 to 4 years of age.

Health Canada has no restrictions on eating fish and shellfish that are lower in mercury. These include salmon, rainbow trout, pollock, herring, shrimp, mussels, clams, oysters, and canned "light" tuna.

Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas.