Dexter Russell offers many fillet knives with different combinations of handle material and blade length. Your choice of either a SofGrip, Sani-Safe, V-Lo, or Traditional handle with a 7", 8" or 9" blade. Each fillet knife contains flex points within the blade that allow the blades to bend easy when in use and returns back to its original shape.
It is ideal to use a 7" blade when filleting smaller fish like, crappie, perch, and bluegills, because you will have better handling and control.
Larger fish like pike, tuna, and salmon require a longer blade to accommodate for the extra girth and surface area of the fish.