RE:Gregg's adjustable fillet knife
The company is Cutco out of Olean NY and the model is The Fisherman's Solution. It has a 6" razor sharp blade that extends out to 9" and is fully removeable for cleaning. The sheath has sturdy snaps, a snap open belt loop, a hook and blade sharpening stone, a notch cut in the sheath safely exposing a piece of the blade to cut line without removing the blade from the sheath, and the sheath doubles as a rough pair of pliers.
The web link is http://www.cutco.com/main/solution1.html