#6428 Large Damascus Fillet Knife – A fillet knife is used to remove the flesh from the bones of the fish.  Other areas you can use a fish fillet knife are; Cutting chicken: besides the hard joints and bones, a fillet knife can be handy when slicing chicken, especially the breast pieces. It helps you get thin slices, and you can use it to remove any fat. You can also use it to open up chicken pieces to make them large.