What?? Farm-raised salmon is not the best choice. First of all it is taken out of its natural environment, which means for the salmon it has to rely on what the farmers give them for food. parasite infestation is much more common on farm-raised salmon then on salmon raised on its natural environment.
First of all --- what is this about mercury content? If you are referring to tuna, then just for the record, CANNED tuna is what contains high mercury content -- Fresh caught tuna in its natural environment is absolutely SAFE. I eat raw tuna sashimi almost daily.