don't doubt it would kill parasites but the fish were catching off morehead arrive in japan usually with 48 to 72 hours after off-loading at the dock. None are frozen... you can double check this with your buyer, I did. As far as "all" fish in the sushi bars being frozen it depends on the quality of the restaurant.... strip mall sushi bars = frozen.... 4 star joints will often only serve fresh fish. Their is a couple restaurants with in a hour from the house that buys from a few boats come yellowfin season. with the yellow fin you can tell its fresh by the absents of the gassed pink color that will stay pink even after the meat starts to rot, not to mention the flavor and texture are far superior.