The Rockies recalled Castano from Triple-A Albuquerque to serve as the 27th man for Sunday's doubleheader against the Mets.
Castano was claimed off waivers from Seattle on Tuesday and will now receive his first look in the majors with his new organization. The right-hander has allowed one earned run over 7.1 innings at Triple-A between Albuquerque and Tacoma.