Here is a good quick way of dealing with kahawai. I often turn them into steaks. Start off by scaling the whole fish. Then cut straight across the body cutting steaks about 25mm thick. Then freeze on a wire tray covered with a plastic supermarket bag. A few hours later after they are frozen take out of the freezer and dip each steak in cold water, then freeze again. Do this several times so that a thick layer of ice encases the steaks. This prevents freezer burn. Finally you can tip all the steaks into a bag so they are free-flow packed.