Pat the tilapia fillets completely dry using paper towels to ensure the spices adhere and the fish sears properly.
In a small mixing bowl, whisk together the paprika, onion powder, garlic powder, oregano, thyme, cayenne pepper, salt, and black pepper.
Brush both sides of each tilapia fillet generously with the melted butter.
Coat both sides of the fillets with the spice mixture, pressing gently so the seasoning forms a thick layer.
Heat a large cast-iron skillet over high heat until it is very hot and just beginning to smoke.
Place the fillets in the hot skillet and cook for 2 to 3 minutes per side, or until the spice crust is blackened and the fish flakes easily with a fork.
Remove from heat immediately and serve with lemon wedges.