Place saute pan over medium-high heat, and add a few tablespoons oil for sauteing. Add the fish, then other ingredients one at a time: chile powder, chipotle, cilantro, hot sauce, and lime juice. Remove pan from the heat when cooked through.
Make the avocado relish by combining the avocados, tomato, jalapeno, red onions, mango, and lime juice.
Fold cooked fish and avocado relish together.
Place the taco shells in a warm oven until warm; remove from oven and fill with combined mixture.