Heat oven to 425°F. Line cookie sheet with foil.
Place taco shells in 1-gallon resealable food-storage plastic bag. Seal bag; crush shells with rolling pin. Add taco seasoning mix; shake until well mixed.
Cut tilapia fillets into 3x1-inch pieces. Add fillet pieces to bag, pressing crumbs onto pieces to coat. Place on cookie sheet. Bake 15 minutes, turning halfway through bake time. Place 2 pieces on each tortilla. Add toppings. Roll up tortillas.