Heat oven to 400° F. Cook the rice according to the package directions.
Meanwhile, in a shallow bowl, combine the paprika, cayenne, thyme, garlic powder, and ½ teaspoon of the salt.
In a saucepan, over medium heat, melt 2 ½ tablespoons of the butter. Add the lemon juice.
Working with 1 salmon fillet at a time, dip the top and bottom halves first in the lemon butter, then in the spices.
Heat a large ovenproof skillet over medium-high heat. Cook the salmon until blackened, 2 minutes per side. Transfer to the oven for 8 minutes.
Stir the corn, parsley, and remaining salt and butter into the rice. Transfer the salmon and rice to individual plates and serve with the lemon wedges.