A fiber laser is constructed with an erbium-doped fiber, which has an elliptical core and is single-moded along the minor axis and multimoded along the major axis. The laser can emit simultaneously several stable lines at room temperatures. The maximum number of lasing lines obtained depends on the number of modes supported by the erbium-doped fiber in the cavity. The separation between the lasing lines depends on the fiber birefringence. The stability of the lasing lines in the presence of anisotropic gain effects in a polarization-maintaining fiber is explored.