Preheat a grill. Brush the fish fillets with olive oil and season with salt and pepper. Grill for about 5 minutes on each side, just until opaque in the center.
In a large bowl, combine the diced mango, red peppers, green onions, jalapeño, olive oil, lime juce, and cilantro. Mix to combine.
Serve the fish with the mango salsa on top.