Many people love to eat fish – for both the taste and healthy fats – but struggle with the fact that fish are a source of harmful mercury, a toxic heavy metal.

Fortunately, empowered with a little bit of knowledge, we can learn how to avoid much of the mercury while continuing to enjoy fish regularly.

The most important piece of information is to understand that large fish tend to accumulate greater levels of mercury than small fish.

This happens because smaller fish have spent their lifetime accumulating mercury of their own, and when eaten, the small fish pass all of their mercury on to the large fish. So generally, the further up the aquatic food chain, the more mercury. Therefore eating smaller fish is the best approach to avoiding mercury!

The Food and Drug Administration in the US has compiled data on the mercury levels of different fish in its report titled “Mercury Levels in Commercial Fish and Shellfish.”

Here is a summary of some of the most common fish for easy reference:

Highest Levels of Mercury

Shark
Swordfish
Tilefish (Gulf of Mexico)
King Mackeral
Tuna
Orange Roughy
Marlin
Sablefish
Halibut

Lowest Levels of Mercury

Cod
Salmon
Haddock (Atlantic)
Herring
Lobster
Atlantic Mackerel
Grouper
Trout (freshwater)
Shrimp
Tilapia

Hopefully this helps ease concerns about exposing ourselves to mercury simply because we love to eat fish!

For more detail on mercury levels in fish, have a look at the FDA report above.