Thaw fish, if frozen. Rinse fish; pat dry with paper towels. Cut fish into four serving-size pieces, if necessary. Sprinkle fish with salt and pepper.
Place fish on the greased unheated rack of a boiler pan, turning any thin portions under to make uniform thickness. Broil 4 to 5 inches from heat until fish begins to flake easily when tested with a fork (allow 4 to 6 minutes per 1/2-inch thickness of fish).
Meanwhile, in a small bowl stir together cilantro, melted butter, lime peel, and lime juice. Spoon cilantro mixture over fish.