I take a lot of fish oil and its very benificial for my health. One of the not usualy reported benifits I have noticed is that it keeps me warm as well as helping me to burn body fat and of course its realy good for my skin. It's good for your heart too but I'm not sure how I notice that.
Anyway I'm hyper-sensitive to mercury and even a small amount of whole fish will adversly effect me and I used to avoid fish oil for this reason but since starting fish oil I haven't noticed any ill effects from mercury.
I do take selinium daily as well. I'm not sure how this fits in with mercury but be careful not to take too much selenium.
Regards, Anthony