Combine all the ingredients for the seasoning in one bowl and mix it well. Spread the seasoning on a cutting board covered with parchment paper.
Pat the fish fillets dry with a paper towel.
Dip a fillet in melted butter on both sides and let some access butter drip off. Place the fish in the seasoning and coat it evenly on both sides. Repeat with the other fish fillet.
Pour leftover melted butter into a cast iron skillet and spread it around.
Cooking In The Oven:
Preheat the oven to 425° and place the empty skillet in there to preheat for a few minutes. Take it out and add seasoned fish fillets.
Bake fish for 12-13 minutes.
Cooking Under Broiler:
Turn on broiler to high and let it preheat for a few minutes. Set the rack so the skillet is about 5 inches away from the broiler, which is usually the top spot. Preheat the skillet in the hot oven for a few minutes and then take it out to add the fish.
Cook for about 5 minutes and flip the fish. (Use a metal fish spatula to flip.) Cook for another 5 minutes and take it out.
On The Stove:
Preheat the skillet over medium-high heat first. Add the fish and cook it for about 4 minutes on each side.