Mercury In Fish Oil Capsules

This may be a ridiculous concern, but does anyone know anything pertaining to the levels of mercury in fish oil, and if it is something to worry about?

It is not. Perform a search on this site of John Berardi articles - there is one in which he lists the reputable fish oil capsule makers. At least in these more reputable capsules, the levels of iron are nominal - as they are filtered out during the process.