In a mixing bowl, combine olive oil, chili powder, cumin, and garlic powder. Rub the mixture over the fish fillets.
Grill the fish for about 3-4 minutes on each side, until fully cooked.
Warm the tortillas on the grill for about 30 seconds on each side.
Assemble the tacos by placing grilled fish on each tortilla, then topping with shredded cabbage, pico de gallo, and a dollop of sour cream. Serve with lime wedges.