Well, I'm up to 6 capsules of fish oil per day, and I don't feel any weird side effects.

As for brands: there is a 3rd party website that is independent (as far as I could find out) and tests a number of brands on quality, purity, etc. Manufacturers voluntarily enter the program.

The website is http://www.ifosprogram.com/consumer-reports.aspx

The higher quality oils do tend to cost more - no surprise there - but I just did not want to take a risk, and went for a "5-star" brand.

I don't know if it's snake oil (well, originally, snake oil was full of omega3 fats, but that's another story ), but I don't think so. The brand I take is from Norway too BTW.