To serve a whole fish, lay it out flat on a plate and slice through the fish where the head meets the body, until the knife meets the backbone. Repeat at the tail end. Slice through the fillet in the centre, separating the top fillet into two mini fillets, one either side of the backbone. Then slide the knife underneath to ease the flesh of one mini fillet away from the bone, trying to keep it in one piece, if possible. Repeat with the other mini fillet. Lift the tail and pull up toward the head, easing the backbone away from the bottom fillet.