Geesh, I meant to say does NOT repeat on me, typed too fast.
I like it and it is the only one that does repeat on me. It actually "tastes" pure.
My favorite brand, and I feel it is very safe is "Carlson" Liquid Fish Oil. It has really helped me and I really trust the "Carlson" name.
True, there is not perfectly pure body of water, I don't see how there could be, I would think it all gets "mixed" together eventually.
Nordic Naturals is the best I know, but still, there's no body of water in the world free of mercury. It's everywhere.
The mercury issue is exactly why my naturopath and others advise only certain brands of fish oil. They are reputable brands which are known for having good testing standards and tell which waters they fish from.
I'd be surprised if any of them are free of mercury, at this point.