This question already has an answer here:
So it has been widely accepted that raw fish or "Sushi-graded" fish must be frozen below $-37C$ for a certain period before they can be defrosted and eaten raw. I have heard that even fresh fish must go through the freezing process to ensure bacteria are killed
I am just wondering can't we do this with just regular frozen fish in the supermarket provided it doesn't have other preservatives?
I mean in ancient times, the Japanese people didn't have commercial freezers and thermoeters to make all these measurements, so what did they do to ensure that their fish is "sushi-graded"? Something tells me the answer is simply just eating it fresh and raw.
Any sushi-chefs or someone who prepares a lot of sashimi can help?