A good quality sheath knife costing around £70 with a strong back to the blade would be a good start,Stainless steel blades af good quality do have carbon in them and this means the blade is rust resistant but holds a bloody good edge,when you sharpen the blade don't make the cutting edge to thin or the blade will crack, the fiskar knives are great knives for butchering your catch but in the field I would say a strong blade from say Boker would be a safe bet,had one for around 20 yaers no problems,as has been said before, there is no real need for a gut hook but if needed, try a fixed blade ty