Here is an interesting piece from the NC Health Dept. regarding the safety of eating fish. Some fish contain more mercury than others.
While not discussed here, there is a question about fish caught in the Pacific that may have been contaminated by the explosion of the nuclear plant in Japan.
Yes, eating fish is safe, as long as the fish is wild caught and is not from China.
Unfortunately, the US market has been invaded by cheap farm raised Chinese fish.
China is a different culture where they won't care at all about what they are selling you. We have had lots of problems with their toys contained dangerous chemicals, with their construction materials containing corrosive chemicals, and so forth.
Don't even buy porcelain dishes, frying pans, and anything made for cooking from China. No matter how good the brand name is and how the company swears that their product "are safe"... if it's coming from China, you are putting your health at risk. (Who knows how many times their products have been found as unsafe, but the US government just keeps silence while removing the poisonous product from the market, because trade agreements and avoiding scandals.) Cooking products from India, Brazil, Mexico, and so forth are safe, they do keep the safety standards, China is a different story.
Going back to topic, spend more money buying wild caught fish.