fresh tuna, yeah. canned tuna is pretty safe. the fish used in canned tuna is too young to have accumulated dangerous levels of mercury... or so I have read.
I read an article a few years back from MM2K that analyzed about ten major brands. The only one that was clean from additives, chems,insects was Bumble Bee.
Also, eating ass is good for you, as long as there's a pussy on the other side.