The Marlins made the move Monday. Last season's National League rookie of the year was scheduled to start Wednesday against the Dodgers.
The 21-year-old Fernandez is 4-2 with a 2.44 earned-run average in eight starts.
Fernandez made 28 starts last year, going 12-6 with a major league-best .182 opponents' batting average. His 2.19 ERA was second in the majors behind three-time defending ERA champ Clayton Kershaw. Fernandez struck out 187 in 172 innings.
The Marlins recalled left-hander Dan Jennings from triple-A New Orleans. He made 79 relief appearances for the Marlins over the previous three seasons, going 3-5 with a 2.96 ERA.
The Baltimore Orioles placed catcher Matt Wieters on the disabled list with a right elbow strain. Wieters is batting .308 with five homers and 18 runs batted in, but he has thrown out only one of 12 would-be base stealers. ... The Orioles also have promoted right-handed reliever Preston Guilmet from triple-A Norfolk, Va. He takes the bullpen spot of T.J. McFarland, who was optioned to Norfolk. ... Toronto Blue Jays closer Casey Janssen has been activated off the 15-day disabled list. Second baseman Chris Getz was designated for assignment to make room for Janssen, who had a sore back. Janssen posted a career-high 34 saves last season, going 4-1 with a 2.56 ERA in 56 appearances. ... The Washington Nationals have placed first baseman Adam LaRoche on the 15-day disabled list because of a strained right quad. LaRoche joins Nationals third baseman Ryan Zimmerman and outfielder Bryce Harper on the DL.