When you eat a fish, you don't just eat that fish, you eat every fish that fish has ever eaten

Which is why long-living fish are the most contaminated with mercury. Its called bio-accumulation. Long-living fish have more mercury because it builds up in them, from all the smaller fish they eat. And then, it builds up in you. Which is why "Good Housekeeping" asked "How safe is seafood?" in its April issue. And excerpt...

"The biggest health hazard is mercury, a toxic heavy metal linked to neurological problems in developing fetuses and children. Long-living fish have the highest concentrations of mercury. Last fall, reports from both the Institute of Medicine and the Harvard Medical School agreed with a 2004 governmental advisory that four mercury-tainted fish - shark, swordfish, tilefish (also called golden snapper or golden bass), and king mackerel - should never be eaten by pregnant women, women who may become pregnant, nursing mothers, and kids under 12."

"If you're adding more seafood to your family's diet, vary the menu to reduce the risk of mercury contamination from a single source; choose low-mercury varieties like catfish, shrimp, and scallops; and switch to chunk light tuna, which usually averages one-third the mercury levels of albacore."

In addition, in an article called "Know your fish," Good Housekeeping said...

"While the FDA and EPA issued a joint advisory in 2004 warning against the dangers of consuming specific mercury-contaminated fish, it applied only to three vulnerable groups: women who are of may become pregnant, nursing mothers, and children under 12. But after vetting information and warning from a variety of experts and non profit organizations, concerned with levels of mercury and PCBs, we concluded that there is a significant body of concerned consumers currently limiting their fish choices."

"The Safest Choices
These fish and shellfish are low in mercury, PCBs, dioxins, and other contaminants.
Catfish (U.S. farm-raised), Clams, Cod (Pacific), Crab, Haddock, Halibut (Pacific), Herring, Lobster, Mahimahi, Mussels, Oysters, Pollack, Salmon (wild, canned), Sardines, Scallops, Sea bass, Shrimp, Squid, Tilapia, Trout (farm-raised), Tuna (canned light)"

"Be Very Cautious With These
According to both the EPA and the FDA, women who are of may become pregnant, nursing mothers, and children under 12 should avoid these fish because of the levels of mercury contamination in them.
King mackerel, Shark, Swordfish, Tilefish (also called golden snapper and golden bass)"

Said it before and said it again, until we clean up mercury emissions, you have to be conscious of what you eat. Stay safe out there.