Recipes for raw or rare fish dishes, like sushi, seviche, or John Ash’s fresh tuna burger, often call for sushi- or sashimi-grade fish. These interchangeable terms sound like they might be official grades (like Prime or Choice for beef), but there’s actually no official definition or government enforcement for how they’re used. Within the seafood industry, they’re generally applied to fish that’s very fresh or frozen, making it somewhat safer to eat raw compared with other, less fresh raw fish.
Because these labels aren’t a guarantee of quality or freshness, it’s important to buy from a fishmonger you trust. When you’re at the counter, mention that you’ll be eating the fish raw; that way, you’ll probably get a more honest recommendation on what’s best (and safest).