The best length for a blade will depend on what you will be using the knife for. If you plan on catching and cleaning mostly small fish, a shorter blade will work for you. The shorter blade will give you more control to clean around the tiny bones. If you are catching larger fish, a larger knife will easily slice through both scales and skin to make steaks and cutlets. The best way to decide on the length of your knife is to look at the fish’s body from its back to its belly. You want the blade of your knife to be just a little longer than the depth of a fish’s body at its widest point. Matching the blade length to the depth of the fish will ensure your knife can go through the fish completely giving you a single, clean cut. This will also guarantee you are getting the most out of your fish and not wasting it.