Use paper towels to thoroughly dry excess moisture from 4 halibut fish fillets.
In a bowl, combine 2 tbsp melted butter, lemon juice and zest from 1 lemon, and 11/2 tsp kosher salt. Stir to combine. In a separate bowl, combine 1/2 tsp kosher salt, 1 tsp paprika, 1 tsp garlic powder, 1 tsp onion powder, and 1/4 tsp black pepper. Evenly press spice mixture onto both sides of fish fillets.