The Japanese word "Ko" means “small” or “short” in English, and the Ko-deba is a small Deba that is commonly used in coastal areas of Japan to fillet and butterfly small saltwater fish. The Ko-deba is useful knife for home cooks that prefer to clean and fillet the smaller sizes of fish, including small freshwater fishes such as trout.

The Japanese word "Ko" means “small” or “short” in English, and the Ko-deba is a small Deba that is commonly used in coastal areas of Japan to fillet and butterfly small saltwater fish, particularly Aji (Japanese horse mackerel) - hence the alternative name of Aji-deba, or Aji-kiri. However, it is just as adept at dealing with small freshwater fish, such as trout. The Ko-deba is useful knife for home cooks that prefer to clean and fillet the smaller sizes of fish themselves, rather than buy fish which have already been filleted.

Ko-deba are most commonly available in blade lengths of around 100mm to 120mm.