A Razor Might Be Sharp Enough !
There's no substitute for carbon steel. One day I'll discuss how I sharpen my knives. With time and a lot of patience I slowly reveal the pure flesh of the fillet, only removing the skin, fat, red muscle and sinew. Keeping the whole fillet as thick as possible. As a commercial filleter it would take around 20 minutes for me to produce 2 skinless boneless fillets from a whole fish. This was quite wasteful and the belly was often thin and unusable. Today it takes me about an hour to produce those same 2 fillets with almost zero waste. The bellies are always as fat as possible and always usable. They are my favourite part of the fish.