Coming in 4 and 6 inch the Penn Fillet knives are a good cheap knife that stays sharp. The Penn fillet knife with Sheaf is made from a high- carbon stainless steel blade that has a and non-stick coated blade that increases efficiency. The Penn fillet knife also has integrated titanium that resists rust and corrosion.
The Penn knives also have nonslip-grip handles for safer usage even when wet.