I wouldn't. There are several fish that are considered safe during pg, bfing and childhood: frm-raised tilapia, f-r trout, and wild pacific salmon.
There are others but those are the ones that are generally considered safe.
Much as I miss it, I swore off tuna completely (and other large breed fish) when ttc, through pg and as long as we're BFing, because of the research I've read showing how mercury poisoning and autism have such similar symptoms. (It's not necessarily that mercury causes autism, it's that mercury is a toxin and once it's built up in the brain, it results in a poisoning that causes the same devastation as autism. Does that make sense? IOW, it's just as bad if not worse.)
As I understand it, babies' livers aren't developed enough to create bile needed for toxin removal, so mercury goes to the brain and remains there.Doesn't take much for it to build up to a toxic level either. It's the same reason why some meds are dangerous during BFing -- baby can't fllush it out of her system, so it can build up to toxic levels fast.
Does that make sense? It's a personal choice, but I wouldn't recommend ingesting any large breed fish, no matter how it's packaged....
I guess the canned tuna is better than the fresh as far as mercury content.....but I have been known to buy fresh sashimi-grade chunks of the stuff for myself, bring it home, cut it up into pieces, and eat it raw with some soy sauce and wasabi.