Preheat oven to 400°F. Lightly grease one 8x12 inch baking dish.
Rinse fish fillets under cold water, and pat dry with paper towels. Lay fillets side by side in the prepared baking dish. Pour the salsa over the top, and sprinkle evenly with the shredded cheese. Top with the crushed corn chips.
Bake, uncovered, in the preheated oven for 15 - 20 minutes, or until fish is opaque and flakes with a fork. Serve topped with sliced avocado and sour cream.