A sushi chef has to spot the best-quality fresh fish instantly. My method is to look at a fish’s eyes, body, and color. The fish’s eyes should always be bright and clear, not dull and cloudy. Next, I look at the body. Does it shine? Does it look metallic and clean? It should be firm and spring back when touched. The scales should look perfect and even; if a fish has missing or damaged scales, I don’t buy it. The gills should be a vibrant red. If a fish is old, the gills will have a faded, dull, brick-red color.
There are lots of details to consider: Small fish such as aji (Japanese mackerel) and iwashi (sardines) should have a curved shape. Medium fish such as buri (adult yellowtail) and kampachi (amberjack) should have a rounded shape from back to stomach. White fish such as suzuki (Japanese sea bass) and hirame (halibut) should have a rounded shape from head to back. Large fish such as tuna are shown already cut into fillets and bought by the block. Fillets should be almost transparent. Avoid tuna that looks rainbow-colored or black. Whenever possible, buy a fish whole. With tuna this isn’t practical; with smaller fish it is.
Shellfish is better to buy live. In the U.S., because we eat oysters and clams raw, it is very important that they are alive before we prepare them. It’s important to look for a closed shell. If a clam is alive, the shell will be closed. Never buy clams if the shell is open. You can also tell if a clam is alive by taking two clams and tapping them together. If they make a light tapping sound then the clams are dead; if they make a heavy tapping sound then they are still alive. Listen and enjoy!