The Japanese knife used for filleting fish and cutting through small bones is the deba. Its broad, thick blade is built for fish preparation, including beheading, separating fillets, and working carefully along the rib bones.
The deba bōchō first appeared during Japan's Edo period in Sakai, a city renowned for blade-making. Traditional deba knives usually have a single-beveled edge, often with a hollowed ura side. This geometry lets an experienced cook make controlled cuts while guiding the blade against the fish skeleton.
Several forms exist. The hon-deba, meaning “true deba,” is the heavier, sturdier model; the ko-deba is a smaller version suited to small fish. Deba blades can be remarkably thick, allowing them to handle thin fish bones that would damage a delicate slicing knife.
The alternatives describe different tools. A nakiri is primarily a vegetable knife, and an usuba is a professional single-bevel vegetable knife. A yanagiba is a long, narrow sashimi knife designed for clean slices of raw fish, not for chopping through bones. A deba should still not be used to chop large beef or pork bones.