Triple-A Jacksonville placed Neidert on its 7-day injured list Aug. 9.
Neidert was demoted to Triple-A earlier this month after he struck out three and allowed two runs over five innings in a spot start with the Marlins on July 30. The right-hander might have been a candidate to rejoin the big club if the Marlins' rotation depth was further tested in the weeks to come, but his injury will take that possibility off the table for the time being.