Correct, however they do exist and some higher-end restaurants use them. Places usually advertise them as 'super freezers' that operate at -60C, some of the michelin star type restaurants go deeper with medical cryocoolers. It's becoming more common now that places like NYC have a regulation requiring freezing (where before a restaurant could just source from a parasite-free supplier).

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Sushi in the us has to be held at -20C for 7 days, or -35C for 15 hours. They absolutely sell extra cold freezers that go to that temperature. Your home freezer won't.

> I’d wager the vast majority of sushi restaurants are using regular freezers.

After the 7 days at -20 the fish can just be transferred to a regular freezer. So you're right, most places probably don't have the special freezer in house.

No, it’s -4 for 7 days. Any commercial freezer gets that cold. Mine is a cheapo Avantco and goes to -8.

-4F is -20C.

Ha oh yeah. Missed the units.

Well yeah every freezer does that.