In return for Fister, the Tigers received young starter Robbie Ray, reliever Ian Krol and infielder Steve Lombardozzi (since traded), none of which figured prominently in the outcome of this season.
The organization outlined the flurry of moves on its Twitter account and said another move would be announced Tuesday.
The injuries constitute a blow to the AL Central-leading Tigers as they try to hold off Kansas City for the division lead.
In his last two starts, prized Tigers prospect Robbie Ray lasted a combined 7 1/3 innings and gave up a total of 12 earned runs on 15 hits.
Robbie Ray, a rookie filling in for 2013 ERA champion Anibal Sanchez, certainly made the most of his two starts in the big leagues.
Ray got a standing ovation when he left the game Tuesday night.
Alex Avila can understand how Astros batters struggled to hit Robbie Ray’s deceptive fastball; at times Avila struggled to catch it.
Tonight will be a night that Tigers pitcher Robbie Ray never forgets…
Ray will take the spot of 2013 ERA champion Anibal Sanchez, who is on the 15-day disabled list with a laceration on his middle finger.
General manager Dave Dombrowski knows many people will not like this trade.