Deba Deba means “short fat tooth” and this describes the shape of the knife. This is the first knife a sushi chef would use when preparing fish. It is used to fillet fish and butcher the boneless meat. The Deba is a traditional Japanese blade that is only sharpened on one side. This is called “single bevel.” Don’t let the shape and weight of a Deba fool you; they are nimble and precise. Choose the length of your Deba based on the size of fish you’ll be butchering most often.