Prepare the Fish: Preheat your grill or a non-stick skillet over medium heat. In a bowl, mix together olive oil, chili powder, cumin, garlic powder, salt, and pepper. Rub this spice mixture onto the fish fillets.
Cook the Fish: Place the fish on the grill or in the skillet. Cook for about 3-4 minutes on each side, or until the fish is cooked through and flakes easily with a fork. Once done, remove from heat and set aside.
Make the Pineapple Salsa: In a mixing bowl, combine the chopped pineapple, red onion, cilantro, lime juice, and minced jalapeño. Toss well to combine and set aside to let the flavors meld.
Warm the Tortillas: In a dry skillet, lightly warm the corn tortillas for about 30 seconds on each side until they are pliable. You can also wrap them in a clean kitchen towel and microwave them for about 30 seconds.
Assemble the Tacos: Flake the cooked fish into bite-sized pieces. On each tortilla, add a portion of the fish, followed by a generous spoonful of the pineapple salsa. Top with slices of avocado.
Serve: Serve the tacos immediately while warm, with extra lime wedges on the side for drizzling.