One Fish, Two Fish…How Much is Too Much?


We often hear about the health benefits of fish, but then we also hear that fish contains mercury.  This leaves many people wondering is fish good for you and how much is safe? 

Mercury occurs naturally in the environment and it also comes from industrial pollution.  This mercury accumulates in water, turns into methylmercury and then is absorbed by fish.  Over time, these mercury levels build up in fish, particularly large fish which have a longer lifespan and those that feed on fish that contain higher mercury levels.

When we eat fish, we can build up mercury levels in our bloodstream and this can have a serious impact on our health.  These effects are more severe in fetuses, infants and children because it can affect the development of the brain and nervous system.  In adults, mercury poising can impair peripheral vision, speech, hearing, walking and may cause muscle weakness and lack of coordination.

Since each type of fish contains very different mercury levels, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) have developed recommendations for selecting and eating fish and shellfish. 

The general guidelines for fish consumption for pregnant women, infants and children are as follows:

  1. Eat up to 12 ounces per week of fish that are low in mercury.
  2. Avoid fish with the highest mercury levels (i.e. swordfish, shark, king mackerel and tilefish)
  3. Look at local advisories for safety information about fish caught in local waters.  If information is not available, then limit consumption to 6 ounces of fish per week.

Men and women who are not at risk of becoming pregnant may be able to be more liberal with fish consumption.  

For a list of the mercury content of fish, you can click on the following link:


Click here to download a pocket guide of mercury levels in fish: