Combine garlic powder, paprika, coriander, and black pepper. Brush fillets with oil, and sprinkle with spice mixture; spread spice mixture over the top surface of the fish and place fillets on a baking sheet. Broil 6 minutes or until fish flakes easily when tested with a fork.
Combine cilantro, chiles, avocado, and salt in a bowl; lightly mash with a fork.
Divide avocado mixture and fish among tortillas. Serve with lime wedges.