Boning and fillet knives are specialty knives that are essential for some types of food preparation. They feature narrower blades, which enables you to get in close to the bone, keeping food waste at a minimum. Boning/fillet knives cut can through connective tissue and remove meat from heavy bones. They are also useful for removing bones and skin from fish. A flexible fillet knife has a blade that "flexes" slightly to make filleting fish even easier.