From the NRDChttp://www.nrdc.org/health/effects/mercury/guide.asp
Adult men, and women who are not planning to become pregnant, are less at risk from mercury exposure but may wish to refer to the list for low-mercury choices.
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)*