What is the beracha on sushi?
If the fish is clearly recognizable, it a piece of fish should be separated from the mixture, and two berachos should be made – mezonos for the rice, and shehakol for the fish.
However, if the fish cannot be clearly discerned, it is sufficient to recite mezonos on the mixture.
The general rule for a mixture is that we follow the majority, and in this case the majority is the rice.
However, some rule that where the minority is clearly discernible, one should recite two berachos (see Shaarei Haberachah 15:12).
Moreover, in the case of sushi the fish is the main part of the dish, so that if it can be discerned there is room to say that it will not be tafel to the rice, and requires a separate berachah.