Castano was added to the Marlins' big-league roster before Tuesday night's game against the Orioles, Joe Frisaro of MLB.com reports.
This is Castano's first taste of the majors after arriving with the Marlins' organization from the Cardinals in the Marcell Ozuna trade. He's primarily worked as a starter but might take over the Adam Conley role as a long lefty out of the bullpen for the time being.