Preheat oven to 400 degrees F. Lightly grease one 8x12 inch baking dish. Rinse Grouper (or Cod) fish fillets under cold water, and pat dry with paper towels. Lay fillets side by side in the prepared baking dish. Pour 1 cup salsa over the top, and sprinkle evenly with 1 cup shredded sharp Cheddar cheese. Top with the 1/2 cup coarsely crushed corn chips. Bake, uncovered, in the preheated oven for 15 minutes, or until fish is opaque and flakes with a fork. Serve topped with sliced avocado and sour cream.