Fiedler started the season, but was pulled at halftime of the season-opening loss to the Titans after throwing two interceptions in favor of A.J. Feeley.
Feeley started the past two weeks, but has thrown five interceptions in 10 quarters this season for an 0-3 Miami squad.
Fiedler had been Miami's primary starter, when not injured, since Dan Marino retired after the 1999 season.
The Dolphins also placed running back Lamar Gordon on the injured list. Gordon, who was acquired by the Dolphins prior to the season from the St. Louis Rams, was hurt when he was hit by Pittsburgh safety Chris Hope in Sunday night's defeat.
In three games with the Dolphins, Gordon rushed for 64 yards and hauled in 13 passes for 74 yards.