In a bowl, combine all the ingredients of the Cajun seasoning. Set aside.
Heat a cast iron skillet over high heat. To avoid smoke filling the house, you can heat the skillet on the outdoor grill.
Pat the fish dry, coat with the seasoning, then with melted butter.
Put the range hood on, then place 2 fillets at a time into the skillet. (Stand back, because the fish will smoke!) After about thirty seconds, flip the fillets to blacken the other side. Season with salt and pepper. Serve with Pecan Rice and colorful vegetables.
If you have any Cajun seasoning left, store in an airtight container for future use.