I have cleaned, filet, and cooked thousands of pounds of fish per year. Some come in old and I send them back, some are wonderful. Each type of fish has different shelf life, fatty warm water, cold water, lean cold water and warm water all are different, salt water and fresh water. I can tell you that some fish last up to 3 weeks when stored correctly on ice but not wet in a 38=39 degree cooler. Cod and Sword come with worms that when you put on a sizzler under the broiler the worms come out, and yes they are alive. Freezing for 72 hours does kill many things on the fish, but not all. It also makes some species tough when they are cooked. Cod in particular becomes more chewy because the freezing breaks down the cells of the fish. This causes moisture loss therefore dry and tough.
I do not know any mandatory law here in states except for cruise ships flying all flags. All their fish must be frozen with a sworn letter stating that it was delivered frozen and was so for 72 hours prior. When I clean fish and butcher meat and chickens . I find tumors and all kinds of inside blemishes that could be defined as cancers or maybe bruises I don't know and it seems inspectors don;'t care either.
Makes for a crispy garnish. Yecccch.
