Combine the sea salt, black pepper, paprika, garlic powder, oil, tequila, agave and lime juice in a shallow bowl or resealable plastic bag. Add mahi mahi and marinate in the refrigerator for 3 to 4 hours but no more than 12 hours.
Remove the mahi mahi from the marinade; discard marinade. Grill over medium heat until just done, appoximately 5 minutes per side.
To prepare the salsa: Roast peppers over open flame of gas store or grill with high heat until charred on all sides. Place chilies in a resealable plastic bag for 5 minutes. Peel off skin with sharp knife; dice chilies and place in mixing bowl.
Add onion, mango, avocado, cilantro, garlic salt, ground cumin, smoked paprika and lime juice to chilies. Mix well. Refrigerate until ready to serve. Spoon salsa over grilled mahi mahi and garnish with queso fresco.