The 26-year-old Salas, also a right-hander, had a team-leading 24 saves and a 2.28 ERA last year. This year, he's 0-2 with a 6.32 ERA in 18 appearances.
Fick was expected to be in uniform Saturday night against the Phillies, making his major league debut.
Fick, 26, was a 15th-round draft pick in 2007 out of Cal State-Northridge, and was 1-0 with a 3.86 ERA and two saves in a team-leading 21 appearances in Memphis.
His 2.30 ERA last year with Memphis was the fourth-best among Triple-A relievers with 50 or more appearances.
Fick is the son of Chuck Fick, a longtime Cardinals scout, and the nephew of former major league infielder Robert Fick.
Information from The Associated Press was used in this report.