Fish pie is a traditional British dish. This pie is usually made with white fish, for example cod, haddock or halibut. It is oven baked in a pie dish but not usually made with the shortcrust or puff pastry casings that is associated with most savoury pies (e.g. steak and kidney pie).In place of a pastry casing enclosing the pie, a topping of mashed potatoes (sometimes with cheese or vegetables such as onions and leeks added) is used to enclose the contents during baking.Usually, the pie is baked in an oven.