In a small bowl, whisk together 1 tablespoon of lemon juice, olive oil, chili powder, cumin, salt, and pepper. Pour over fish.
Turn fish to coat with the marinade, then cover and refrigerate while preparing the salsa.
Dice pineapple, peppers, and onion; chop cilantro. Add these ingredients to a small bowl, along with the zest of the lime (about 1 tablespoon); set aside.
Drain fish of excess marinade and bake for 15-20 minutes or until it flakes easily when pulled back with a fork. (The time will vary depending on the thickness of the fish.)
Transfer cooked fish to a cutting board then cut or flake into 1-inch pieces.
Serve fish wrapped in warmed tortillas and topped with pineapple salsa.