Tilapia has gotten some bad press lately, but it all depends on where it is farmed - or where
in this case Applebees bought there
fish. See this link to snopes - http://www.snopes.com/food/warnings/tilapia.asp
I guess you could call the manager at Applebees and see where the fish came from.
But since you ate around the uncooked part, that should have been helpful. And I doubt that that part of the fish was uncooked, but rather undercooked.