If you find this is because it was farmed fish and farmer fish can't have this type of inner parasites that cause trouble. Although is true than can have more load of external parasites in skin or gills they are super-clean inside normally. Much cleaner than wild fishes.
I bet that most, if not all, decent restaurants in Japan ultra-freeze wild fishes on the other hand, even if they may not admit it.
> The Health, Labor and Welfare Ministry has issued an official warning on the rapidly growing number of Anisakis infections linked to eating raw or undercooked fish. [...] The ministry urges consumers to keep the fish frozen below minus 20 degrees for at least a day, or heat it for at least for a minute in temperatures exceeding 60 degrees, which should kill the larvae.
My understanding is that for many fish species, the fish are caught well offshore on multi-day fishing trips. They are put on ice immediately, otherwise they return to the docks with spoiled fish. Think "The Perfect Storm".
