In a medium bowl, combine the diced mangoes, tomato, onion, jalapeno, and cilantro. Stir in the lime juice and salt to taste. Combine well and set aside.
For the Blackened Fish
Heat a cast iron skillet or heavy bottomed non-stick skillet over high heat for several minutes until VERY hot.
Working one piece of fish at a time, dip into the melted butter, coating both sides. Then dredge lightly through the blackening seasoning blend.
Place the seasoned fish into the hot skillet and cook for 2 to 3 minutes. Carefully flip, and cook another 2-3 minutes. To prevent blackening seasoning from building up, carefully wipe the skillet out between each piece. Transfer to a platter, cover with foil, and repeat until all pieces of fish are done.
When ready to serve, slice the fish into strips. On a warm tortilla, add cabbage, fish, optional sauces and top with the prepared mango pico.