Contrary to popular belief, fish is not a health food. Fish flesh contains toxins from the water that fish live in, and those toxins get passed on to people who eat fish. Fish raised on farms are given antibiotics, which are also passed on to consumers. According to the Centers for Disease Control and Prevention, 325,000 people in the U.S. get sick or die every year from eating contaminated fish and other sea animals. Even if you could be sure that the fish you eat were free of chemicals, the flesh of some sea animals, especially shrimps and scallops, contains even more cholesterol than beef!
As an alternative, you can enjoy seaweeds (such as nori and dulse), and flax oil is an excellent source of omega-3.