I say that most sushi restaurants in N America go by using sushi grade fish that was probably processed by a fish monger, not the chef.
Aging fish really comes into play for high end sushi, where the chef is after some chemical reactions can only happen over time, it's not rot, it's more like it had time to rest and develop flavors that it would not have had if it was just straight from the fish right after it was caught.
Aging fish really comes into play for high end sushi, where the chef is after some chemical reactions can only happen over time, it's not rot, it's more like it had time to rest and develop flavors that it would not have had if it was just straight from the fish right after it was caught.