Mercury: Fish to Avoid

Mercury: Fish to Avoid

How much mercury does this fish have?

Fish can be a part of a healthy diet (but are by no means essential to a healthy diet, so vegan friends keep on vegging out!).  Unfortunately, many popular fish are high in mercury.  Mercury is a heavy metal that we do not need in our systems to survive.  In fact, there is no safe amount of mercury that we know of.  As parents, we have an obligation to protect our children as much as possible.  One way to do this is to avoid feeding kids fish high in mercury.  Pregnant women also need to avoid mercury as much as possible, as mercury can cross the placental barrier.

Fish as a Source of Mercury

Preparing fish

While some mercury is naturally discharged into the environment, much mercury is added to the environment by human industry.  Industries often discharge large amounts of waste products into our water sources.  Elemental or inorganic mercury is discharged by industry into our oceans and is transformed by bacteria into methylmercury.  This methylmercury then accumulates in the aquatic food chain.  Thus, small animals eat the bacteria, bigger animals eat them, and as you move up the food chain more and more methylmercury accumulates in the fish. Pregnant women who eat this fish, or children whose parents feed them this fish, are at higher risk. (Read more here.)

Which Fish to Eat?

Grilled fish

Not all fish accumulate methylmercury equally.  Just as not all mammals eat the same things, not all fish eat the same things.  If the methylmercury processing bacteria aren’t in the food chain (or are less in the food chain), then the bigger fish will contain less mercury.

Unfortunately, overfishing has also done a lot of damage to the aquatic environment.  Some fish are being so overfished their populations are declining dangerously.  This isn’t a health or diet issue, but it is an environmental issue.  Because this is a nutrition blog, I’ll still list fish with dangerously low levels or with bad environmental fishing practices, but I will include the caveat of stars for those who wish to avoid them.

This list is from the Natural Resources Defense Council.

LEAST MERCURY

Enjoy these fish:
Anchovies
Butterfish
Catfish
Clam
Crab (Domestic)
Crawfish/Crayfish
Croaker (Atlantic)
Flounder*
Haddock (Atlantic)*
Hake
Herring
Mackerel (N. Atlantic, Chub)
Mullet
Oyster
Perch (Ocean)
Plaice
Pollock
Salmon (Canned)**
Salmon (Fresh)**
Sardine
Scallop*
Shad (American)
Shrimp*
Sole (Pacific)
Squid (Calamari)
Tilapia
Trout (Freshwater)
Whitefish
Whiting

MODERATE MERCURY

Eat six servings or less per month:
Bass (Striped, Black)
Carp
Cod (Alaskan)*
Croaker (White Pacific)
Halibut (Atlantic)*
Halibut (Pacific)
Jacksmelt
(Silverside)
Lobster
Mahi Mahi
Monkfish*
Perch (Freshwater)
Sablefish
Skate*
Snapper*
Tuna (Canned
chunk light)
Tuna (Skipjack)*
Weakfish (Sea Trout)

HIGH MERCURY

Eat three servings or less per month:
Bluefish
Grouper*
Mackerel (Spanish, Gulf)
Sea Bass (Chilean)*
Tuna (Canned Albacore)
Tuna (Yellowfin)*

HIGHEST MERCURY

Avoid eating:
Mackerel (King)
Marlin*
Orange Roughy*
Shark*
Swordfish*
Tilefish*
Tuna (Bigeye, Ahi)*

* Fish in Trouble! These fish are perilously low in numbers or are caught using environmentally destructive methods. To learn more, see the Monterey Bay Aquariumand the The Safina Center (formerly Blue Ocean Institute), both of which provide guides to fish to enjoy or avoid on the basis of environmental factors.

** Farmed Salmon may contain PCB’s, chemicals with serious long-term health effects.

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