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Facts on Fish

Fish is good for us.  We are supposed to eat at least 2-3 servings a week, but what kind is best?  How do we avoid increased Mercury levels?  Hopefully, this will help you decide.

About Mercury

Mercury is a toxic metal that is dangerous for developing fetuses and nursing infants.  It is now considered a potential threat to adults as well.  Mercury is a problem when bacteria convert it to methyl mercury, which accumulates in fish (and humans) over time.  While nearly all fish contain some methyl mercury, older, larger, predatory fish by far contain the most.  No food preparation or cooking method can remove it. 

Dangers of Mercury

Mercury damages the brain and nervous system, causing confusion, depression, memory loss and tremors, as well as, fatigue, hair loss and a metallic taste in the mouth. 

Another possible effect of mercury toxicity is an increased risk of heart disease due to increasing LDLs which promotes clotting and increases an inflammatory response. 

Why Fish is Good For You

The good news is: the omega-3 fats found in fish provide heart-protective benefits, such as preventing blood clotting, and decreasing abnormal heart rhythms and reducing triglyceride levels.  This helps to offset the dangers from mercury.  Therefore, the best way to decrease mercury levels is to minimize mercury intake by choosing wisely, NOT stop eating fish altogether.  Mercury levels in the blood can decrease and symptoms (if any) can resolve with a decrease in seafood consumption or just by making smart choices.

FDA Regulations

The Food and Drug Administration (FDA) regulates commercial seafood, while the Environmental Protection Agency (EPA) oversees guidelines for fish caught by recreational fisherman.  Mercury in fish is measured in parts per million (ppm), but safe consumption depends on a person's exposure per unit of body weight.  See Environmental Nutrition's Chart to help you regarding mercury levels and environmentally friendly fish choices.

Environmental Nutrition (EN) Rates Seafood Safety

Each section is listed in alphabetical order.  Seafood listed in parentheses are not as environmentally friendly as the others, especially if Atlantic-caught.  In the chart below, EN's editors have converted ppm of mercury into a safe number of fish servings for each category.  In order to mix and match fish from different categories, don't exceed a weekly total of 0.5 ppm of mercury (pregnant and nursing women and young children should not exceed 0.2 ppm). A serving is 3 ounces.

** = EN's Best Picks (low in mercury and PCB's, highest in omega-3 fatty acids, environmentally friendly)

Choose More Often

Choose Less Often

Very Low Levels of Mercury: <0.1 ppm
(3-4 servings per week)

Medium Levels of Mercury: 0.2 - < 0.3 ppm
(1-2 servings per week)





Crab, king





Sea trout

(Salmon, farmed)

High Levels of Mercury: 0.3 - < 0.7 ppm
(0-1 serving per week)

**Salmon, canned or wild Alaskan







(Orange roughy)


(Red snapper)


(Saltwater, bass)

Low Levels of Mercury: 0.1- <0.2 ppm
(2-3 servings per week)

(Trout, freshwater)

Tuna, fresh


Tuna, canned, white albacore

Crab, Dungeness and blue

Risky Levels of Mercury: > 0.7 ppm
(Avoid or no more than once a month)



Mackerel, king

Mahi mahi


Ocean perch


**Tuna, canned, light




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