Not sure why this is so hard to understand. We don't flash freeze "all the fish". We freeze all the fish that is going to be eaten raw for a specified time at a specified temperature to kill the parasites that can make you sick. Fish that is going to be cooked does not need to be treated, as the cooking will kill them.

What are they trying to prevent? A partial list:


Anisakis simplex (herring worm)
Diphyllobothrium latum
salmon tapeworm (they grow to nine feet long)
Vibrio species (bacteria)
Vibrio vulnificus
Eustrongylides,
Pseudoterronova decipiens
Gnathostoma sp
Capillaria Phillippinensis
Clonorchis sinensis
Opistorchis viverrini
Metagonimus yokogawai
Paragonimus

To name a few. The most common are the first three

If you are really interested, googling will give more details, pictures, infection rates, etc.