1In a saucepan, bring water to a boil with a pinch of salt. Stir in rice, reduce heat to low, cover, and cook for 18 minutes until tender and liquid is absorbed.
2While rice cooks, combine paprika, garlic powder, onion powder, oregano, thyme, cayenne, black pepper, and salt in a small bowl.
3Pat tilapia fillets dry with paper towels. Brush both sides lightly with oil, then coat generously on both sides with the spice mixture, pressing gently so it adheres.
4Heat vegetable oil in a skillet over medium-high heat until it shimmers and just barely starts to smoke—this is crucial for the blackened crust.
5Working with 2 fillets at a time, place them in the hot skillet and sear for 3 minutes without moving them. Flip and sear for another 2 to 3 minutes on the second side until the fish flakes easily with a fork and the spice crust is dark and caramelized.
6Transfer cooked fillets to a plate and repeat with remaining fillets.
7Fluff the finished rice with a fork and stir in butter.
8Divide rice among plates and top each with a blackened tilapia fillet. Serve with lemon wedges.