Almost all of the fish oil you can buy actually comes from 1 company and have been tested for mercury (by ConsumerLab.com and Consumer Reports):<p><a href="http://www.usatoday.com/news/health/2004-12-15-fish-oil-usat_x.htm" rel="nofollow">http://www.usatoday.com/news/health/2004-12-15-fish-oil-usat...</a><p>None of the major brands had significant amounts of mercury.<p>I'd just get the cheapest kind, given that it's likely from the same company.