Make the pineapple salsa: In a large bowl, combine pineapple, onion, jalapeño, cilantro, vinegar, and oil. Toss to coat, cover with plastic wrap and refrigerate for 30 minutes, or up to 2 hours.
In a small bowl, combine paprika, garlic powder, onion powder, salt, oregano, pepper, cumin, and cayenne.
Pat mahi mahi dry and transfer to a large bowl. Spoon over mayo and sprinkle with the spice mixture. Toss fish until completely coated and refrigerate for at least 20 minutes, or up to 1 hour.
Preheat grill to medium high for 3 minutes. Grill fish until charred and fully cooked through, 6 to 8 minutes, flipping halfway through.
In the last minute of cooking, add tortillas to the grill until pliable and slightly charred on both sides. Assemble tacos with a piece of fish, a bit of pineapple salsa, a sprinkle of cilantro, and some lime wedges.
