Discontinuous fiber composites are processed with conventional polymer processing equipment for decades. Although their anisotropic properties are acceptable for most applications, it is often seen that the fiber orientation distribution is not optimized for specific cases. The ability to change the fiber orientation in certain regions of a product can lead to enhanced product properties (structural properties, thermal properties, electrical properties, …). Unfortunately, common melt processing of short fiber reinforced polymers does not allow to control the fiber orientation. Magnetic manipulation of the dispersed phase is a possible alternative technique to achieve optimized composite characteristics. This paper describes the behavior of a single discontinuous ferromagnetic fiber submerged in viscous fluids under an external magnetic field. A FeCralloy steel fiber is placed in a non reactive polydimethylsiloxane (PDMS) matrix. The external magnetic field is applied with electromagnets. The rate of fiber alignment for a single fiber is investigated for different boundary conditions. The influence of the matrix viscosity, the fiber aspect ratio and the magnetic field strength are discussed. Numerical predictions are performed with two micromechanical models incorporating the magnetic and hydrodynamic forces. These models have shown to be effective in the prediction of the dynamic behavior for other fiber types and fiber geometries. The limitations of these models to predict the realignment behavior of multi-fiber composites are discussed at the end of the paper based on experimental data.