We cut a lot of fish. Some for eating and some for bait. In the picture at the top we are cutting a bonito into chunks by cutting in a checkerboard pattern then cutting all of those off the carcass. We will use these chunks for chumming and for baiting our hooks for a host of different species and applications.
Each fish has a way that it is best filleted or cleaned for eating. One thing that is in common with each of these is that you will need a very sharp fillet knife. As you get more involved, you can move from one knife to several which are slightly more specialized for each task. Here are some examples: