In a bowl, mix the smoked paprika, chili powder, cumin, lemon juice, lemon zest, garlic, melted butter, salt, and pepper.
Pour it over the tilapia on a foil-lined baking tray.
Bake the fish for about 10 minutes at 400°F, to an internal temperature of 140°F using a thermometer. (Baking time will vary based on your fish fillet thickness.)