Preheat grill (or grill pan). Peel mango and cut into 1/4-inch cubes (1 cup). Chop onion (2 tablespoons) and cilantro. Squeeze limes for juice (1 1/2 tablespoons). Combine mango, onion, cilantro, lime juice, agave, and 1/4 teaspoon salt.
Combine all spices and remaining 1/4 teaspoon salt. Cut salmon into four equal pieces (wash hands). Coat both sides of salmon with spray and spice mixture. Place salmon on grill (or in grill pan); grill 3–4 minutes on each side and until 145°F (or opaque and separates easily). (Or bake salmon in oven preheated to 400°F for 8–10 minutes.) Serve mango salsa over fish.