I have been playing around with filet knives for different customers lately, and came out with this kind, which I like much. Blade length 180mm, max breadth about 30mm, max thickness 3mm. Blade steel is number 20 from Sandvik, Sweden(1%C). The handle is mexican Bocote. The blade steel is from Sandvik, number 20, plain carbon steel with 1%C. Length is 180mm breadth is 32mm. Maximum thickness is 3mm at the beginning and gradually tapered to 1mm at the point of the back, just before it falls down to the point. It is a play with compound curves outbalanced by the overbuilt handle of mexican Bocote.
here you can see the work on distal taper and blade geometry.
here the knife is resting on his flattened back so we can have a look at the cutting edge.
this is how I like to keep my edges protected form being dulled. for transport the knife thus doesn´t rattle inside his scabbard.