Filleting your own fish is simple when you know how—just use a good sharp knife.
Lay the fish dark-side-up. Cut around the outside of the fish with a filleting knife where the flesh meets the fins.
Cut down the centre of the fish from head to tail with a sharp knife. Make sure you cut all the way through to the bone.
Working from the centre of the fillet to the edge, cut away one fillet with long broad strokes of, the knife, without leaving too much flesh. Remove the other fillet in the same way, then turn the fish over and repeat.