It depends on what kind of sushi are you eating, if it is real sushi made by a Japanese chef or a Chinese fake sushi... and there is a huge difference in quality of ingredients and taste... Japanese are fanatic of perfection.... Chinese..............
Depends also of what kind of fish is used. All Farmed fish in every part of the world is a shit:
Depends also if fish is fresh or frozen with chemical additives. There is no big difference in taste or nutrients between frozen or fresh, also because all fresh fish must be frozen by restaurants (some hours or few days) because of parasites (anisakis). But often frozen fish have many chemical additives.. especially cheap one. There is also top quality frozen fish, you can notice quality of ingredients checking both taste or prices, indeed a good quality restaurant with a real Japanese chef (or someone not necessary jap but who made a real sushi course) with top ingredients can't be cheap.
Wild fish frozen or fresh without additives is the best! As all top quality food!
A fake japanese-Chinese sushi made with tilapia, panga or any other farmed fish is junk food.
