The Rockies reinstated Castano (pectoral) from the injured list Saturday and optioned him to Triple-A Albuquerque.
Castano has been on the injured list since late June due to a pectoral strain. He began playing in rehab games last Saturday and has since allowed four runs on four hits and two walks over 2.1 innings. Now fully healthy, the 27-year-old will remain in Triple-A for the time being but could return to the majors later in the year as bullpen depth.