What is meant by a fillet knife and how can you tell if it’s of good quality? Let's try and figure it out. Fillet knives are knives for filleting (cutting) fish.  They are also often used by hunters as a tool for eviscerating carcasses. Features of fillet knives: flexibility and increased sensitivity of the blade; narrow blade; special shape; sharpening angle - 20 degrees. It is by these parameters you should be guided when choosing a fillet knife.  Plus, also...