Freezing also kills some potentially zoonotic parasites that may be present in fish. Unless you're buying it straight off the docks, or pulling it out of the w

Freezing also kills some potentially zoonotic parasites that may be present in fish. Unless you're buying it straight off the docks, or pulling it out of the water yourself, any unfrozen fish you see has likely been thawed on site, after delivery. "Fresh" fish means that it was frozen on the boat, and just thawed today. I sometimes make nigiri sushi by sawing slices off of a frozen fish filet with a kitchen-use-only coping saw. Then I put it in the fridge for the next day. Comes out fine. If I wanted, I could freeze the rice with it, and have sushi later in the week.