You can bake Mahi Mahi, or any other fish in the oven preheated for 450 degrees. Place fish on a greased shallow baking pan. Brush with melted butter and season as you desire. Bake for 4 to 6 minutes per 1/2 inch thickness of fish. So for a 1 inch thick piece of fish you would bake for 8 to 12 minutes.