Almost any type of fish can be used for sushi, and as mentioned before, experimenting is usually half the fun. In addition to salmon (Sake) a sushi favorite raw, smoked or grilled is tuna (Maguro), an ideal fish for sushi. Its red color and robust flavor stands up well to wasabi. A fancier variety of tuna is Toro, which is actually the belly of the tuna, and is a more expensive than plain tuna. Another traditional sushi fish is Suzuki, of which there is no Western equivalent, but its mild flavor and flaky texture can best be imitated by Sea Bass. Katsuo or Bonito is a beautiful red fish and has a strong flavor to match its striking color. Saba ( mackerel) is not for everyone as it has the reputation for being somewhat fishy and oily, but it is quite good if it is marinated in soy sauce. Uni (Sea Urchin Roe) actually contains the gonads of the fish. It has a salty and nutty flavor but is really roe. There are many kinds of roe, including those famous orange and red balls seen atop many sushi rolls.
Slicing the Fish
The art of sushi making depends on how well the fish is sliced. The thinner the slices are, the better, and slicing the pieces of fish perfectly is the most painstaking part of the sushi making process, and the skill that requires the most practice. Obviously, finding a razor sharp knife is important; the best is a bento knife, a Japanese knife specially designed for slicing sushi. The slicing should be done on top of a thick, wooden cutting board to protect your kitchen counter.
To cut the fish, you need only a light, dragging motion, and the weight of the knife will take care of the rest. For most types of sushi, you will need fillets ¾" wide, 2" long and 1/8" deep.