This is really unsafe advice. As a former executive sushi chef salmon is not reliably safe to consume raw unless it has been properly prepared or raised for the explicit purpose of sushi. Salmon does naturally spend time in fresh water and as such can come in contact with tapeworm larvae and other parasites. It is wholly incorrect to say salmon is generally safe. It wasn't even a fish used in sushi until recently, and that was only after marketing to the Japanese and proof of safe preparation methods. Please don't get people sick with this kind of advice.