In a small bowl, mix paprika, cayenne pepper, onion powder, salt, white and black pepper, thyme, basil and oregano.
Brush salmon filets on both sides with 1/4 cup butter or margarine. Sprinkle sides evenly with the cayenne pepper mixture. Drizzle one side of the filet with 1/2 of the remaining butter.
In a large, heavy skillet, over high heat, cook salmon, butter side down, until blackened, about 2 to 5 minutes. Turn filets, drizzle with remaining butter and continue cooking until blackened and fish is easily flaked with a fork.