1) Preheat oven to 190C/170C fan/gas 5 and brush a baking tray with oil.
2) Make three or four deep slashes on either side of the fish. Put a few slices of lemon or lime inside the body cavity and sprinkle the inside with salt. Drizzle the outside with oil then put the fish on the prepared tray and bake for 25 minutes.
You can see Bill's baked fish recipe here