In a small bowl, whisk together olive oil, lime juice, garlic powder, paprika, salt, and pepper.
Rub the marinade all over the salmon fillets. Let sit for 10–15 minutes while you prepare the salsa.
In a medium bowl, combine diced mango, red onion, bell pepper, cilantro, lime juice, and jalapeño (if using). Season with salt and gently toss.
Preheat grill or grill pan over medium-high heat.
Grill salmon for 4–5 minutes per side, or until it flakes easily with a fork and has nice grill marks.
Remove from heat and let rest for 2 minutes.
Serve each salmon fillet topped with a generous scoop of mango salsa.