Rinse fish thoroughly in cold water; pat dry, and place in a large shallow container.
Combine 1/2 cup melted butter and next 6 ingredients, stirring well; pour over fish.
Cover and refrigerate 30 minutes, turning fish once.
Remove fish from marinade, reserving marinade.
Grill over hot coals 10 minutes on each side or until fish flakes easily when tested with a fork.
Baste frequently with marinade.
Transfer to a serving platter, and pour 2 tablespoons melted butter evenly over fish.