Mercury in Fish: How much fish is too much?

A coworker asked me a great question that prompted me to do some further research. Should I worry about the mercury in fish? First, the most serious threats are for pregnant women and children but still the answer isn't clear. Yes, you should worry, but no eating fish isn't dangerous. A lot of things factor into how much fish you should eat including what type of fish you're eating and how much.

After  researching I learned some great guidelines for getting omega-3 rich proteins from fish without going overboard on mercury. The biggest thing I learned was that canned chunk light tuna contains less mercury than canned albacore tuna. I also learned that at my weight I can have a can of chunk light every 3 days (if I wanted).

Here is a great list of mercury levels in fish from the Natural Resource Defense Council. Their website also has great guidelines for eating tuna safely based on your weight.
Note: These guidelines are not for pregnant women, if you are pregnant I recommend going to The American Pregnancy Association for guidelines on what fish are safe to eat during your pregnancy.

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 Aquarium and the 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.

Sources for NRDC's guide: The data for this guide to mercury in fish comes from two federal agencies: the Food and Drug Administration, which tests fish for mercury, and the Environmental Protection Agency, which determines mercury levels that it considers safe for women of childbearing age.

About the mercury-level categories: The categories on the list (least mercury to highest mercury) are determined according to the following mercury levels in the flesh of tested fish.

• Least mercury: Less than 0.09 parts per million
• Moderate mercury: From 0.09 to 0.29 parts per million
• High mercury: From 0.3 to 0.49 parts per million
• Highest mercury: More than .5 parts per million