Because of high levels of mercury in fish, guidelines have been set up to help pregnant women be aware of the risk:
Consumming raw fish and seafood is not recommended during pregnancy and should be avoided.
Fish with the highest levels of mercury should be avoided completely. These include: Grouper, Marlin, Orange Roughy, Tilefish, Swordfish, Shark, King Mackerel
Fish with high levels should be eaten no more than 3 times per month (6-oz serving size). These include: Saltwater bass, Croaker, Halibut, Tuna (canned, white albacore),Tuna (fresh Bluefin, ahi), Sea Trout, Bluefish, Lobster (American/Maine)
The next level of recommendations are for moderate mercury risk. A woman should eat no more than 6 servings per month (6-oz servings) of:
Carp, Mahi Mahi, Crab (Dungeness, Blue, and Snow), Snapper, Herring, Monkfish, Perch (freshwater), Skate, Cod, Tuna (canned, chunk light), Tuna (fresh Pacific albacore)
Fish that carry lowest risk for mercury exposure can be enjoyed as often as twice per week (6-oz serving). These fish include: Anchovies, Butterfish, Calamari (squid), Caviar (farmed), Crab (king), Pollock, Catfish, Whitefish, Perch (ocean), Scallops, Flounder, Haddock, Hake, Herring, Lobster (spiny/rock), Shad, Sole, Crawfish/crayfish, Salmon, Shrimp, Clams, Tilapia, Oysters, Sardines, Sturgeon (farmed), Trout (freshwater)