Smith was the No. 6 overall pick in the 2009 NFL Draft. He played seven season for the Bengals before joining the Minnesota Vikings in 2016. Smith returned to Cincinnati in 2017 and started eight games for the Arizona Cardinals this season before being waived on Monday.
The 6-foot-4, 325-pound offensive lineman has started 93 games during his 10-year NFL tenure.
Fisher, 25, was a second-round pick by the Bengals in the 2015 NFL Draft. The 6-foot-6, 305-pound offensive lineman suffered a back injury during the Bengals' loss to the Cleveland Browns on Sunday in Cincinnati. He has played in all 11 of the Bengals' game this season, starting once.
Bengals starting left tackle Cordy Glenn is has not practiced this week while he deals with a back injury.