You would have to be living under a rock to not realize that omega-3 fats are useful for you. Unfortunately most of the seafood in the world is contaminated with heavy metals and toxins.   

Fish are now loaded with mercury as a result of industrial pollution. If you eat a lot of fish, you'll want to know how much mercury you may be consuming by using a free online mercury calculator. Mercury stays firmly bound to the sulfur proteins in your brain, causing damage to the microtubules that nourish your brain cells.

If you frequently eat fish and seafood, you need to be aware of where that food is coming from. You probably also realize that farmed fish is something you want to avoid. 

If you go to a restaurant and fish is on the menu please understand that it typically would not be a healthy choice. You might want to educate your friends and family about this so they aren't fooled and deceived.

The major exception to this would be sushi bars where you can order the fish raw, which tends to diminish some of the toxicity.

But now there is another factor you will need to consider if you choose to eat fish. In the last year, the United States increased its imports of seafood from China by 34 percent. Meanwhile, one in four Americans gets hit with a food-borne illness each year. About 20 percent of these cases are due to contaminated seafood.

The irony is, if it weren't for the increasing risk of contamination by substances such as mercury, melamine, and untreated fecal water, fish really would be the optimal food source for omega-3. Fortunately, toxin-free fish oil and krill oil, which will give you the nutritional value your body needs, are still available and highly recommended.