Coutlangus, who appeared in 64 games in relief for the Reds last year, was optioned to Triple-A Tucson following the completion of the deal. Cincinnati had designated the 27-year-old for assignment on March 31.
The D-backs have one left-hander in their Major League bullpen, Doug Slaten, and not much depth in that area at the upper levels of their farm system. Coutlangus has Minor League options remaining so he gives the D-backs flexibility if they want to add a left-hander at some point during the season.
"Lefty with options," D-backs general manager Josh Byrnes said. "Obviously, we're looking for a little more left-handed pitching and a guy with some flexibility. It's a good fit for us because we're pretty right-handed."
Coutlangus was drafted as an outfielder by the Giants in the 19th round of the 2003 First-Year Player Draft. He was converted to a pitcher in 2004 and claimed off waivers by the Reds prior to the 2006 season.
Last year he was 4-2 with a 4.39 ERA for the Reds and his 64 appearances ranked third among all National League rookies.
Perales hit .282 in 136 games for Class A South Bend last year and is currently on the disabled list.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.