Some types of fish may contain high levels of mercury, PCBs (polychlorinated biphenyls), dioxins and other environmental contaminants. Levels of these substances are generally highest in older, larger predatory fish and marine mammals.
The most commonly eaten fish low in mercury are: canned light tuna, salmon, pollock, and catfish.
It is recommended to avoid eating shark, swordfish, king Mackerel, or tilefish (golden bass or golden snapper) because they contain high levels of mercury.
Eating oily fish like Salmon is a great way to increase Omega-3 polyusaturated fat intake.
A picture of salmon with its Omega-3 rich skin
According to FDA, the benefits and risks of eating fish vary depending on a person’s stage of life:
- Children and pregnant women are advised by the U.S. Food and Drug Administration (FDA) to avoid eating those fish with the potential for the highest level of mercury contamination (e.g., shark, swordfish, king mackerel or tilefish); to eat up to 12 ounces (two average meals) per week of a variety of fish that are lower in mercury (e.g., canned light tuna, salmon, pollock, catfish)
- For middle-aged and older men and postmenopausal women, the benefits of eating fish far outweigh the potential risks when the amount of fish are eaten is within the recommendations established by the FDA and Environmental Protection Agency.
Omega-3 and Mercury Levels for Most Consumed Fish in the United States
(data published by American Heart Association, link below)
| |
Omega-3 fatty acids
(grams per 3-oz. serving) |
Mean mercury level in parts per million (ppm) |
| Canned tuna (light) |
0.17–0.24 |
0.12 |
| Pollock |
0.45 |
0.06 |
| Salmon (fresh, frozen) |
1.1–1.9 |
0.01 |
| Cod |
0.15–0.24 |
0.11 |
| Catfish |
0.22–0.3 |
0.05 |
| Clams |
0.25 |
ND |
| Flounder or sole |
0.48 |
0.05 |
| Crabs |
0.27–0.40 |
0.06 |
| Scallops |
0.18–0.34 |
0.05 |
Fish with the Highest Levels of Mercury
(about 1 ppm; data published by American Heart Association, link below)
| |
Omega-3 fatty acids
(grams per 3-oz. serving) |
Mean mercury level in parts per million (ppm) |
Tilefish (golden bass or
golden snapper) |
0.90 |
1.45 |
| Shark |
0.83 |
0.99 |
| Swordfish |
0.97 |
0.97 |
| King mackerel |
0.36 |
0.73 |
FDA Advice on Fish Consumption: http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/Seafood/FoodbornePathogensContaminants/Methylmercury/ucm115662.htm
American Heart Association article entitled “Fish 101” published Omega-3 and Mercury levels for different types of fish: http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/Fish-101_UCM_305986_Article.jsp
