Preheat oven to 375°F (190°C). Lightly grease an 8x8 inch baking dish.

In a large bowl, combine the cooked rice, flaked salmon, cream of mushroom soup, milk, chopped onion, Worcestershire sauce, and black pepper. Mix well.

Spread the mixture evenly into the prepared baking dish. Sprinkle the shredded cheddar cheese over the top.

In a small bowl, combine the crushed crackers and melted butter. Sprinkle this topping evenly over the cheese.

Bake for 25-30 minutes, or until the casserole is heated through and the topping is golden brown.

Let stand for a few minutes before serving.