These fish tend to be the deep, cold water variety. You must couple this recommendation with the cautionary notes that pregnant women be careful about the type of fish they choose to eat because of the risk of heavy metal and pesticide contamination that can accumulate in fish. Fetuses can be damaged by these toxic chemicals. The fish especially rich in omega three fatty acids include mackerel, salmon, trout, rockfish, herring, whitefish, anchovy, and tuna. Pregnant women are warned against eating swordfish, shark or fresh tuna, and all fresh water fish.
Fresh water is more apt to be contaminated than ocean waters.
Of those fish that are okay to eat, eat a variety of them. This will reduce your risk of overdosing on one particular contaminant. Don't eat the fish skin, where toxic chemicals are stored. Choose farm raised fish if possible. While it is true that they contain less omega 3 than other fish, you are more certain they do not contain toxins.