The ornamental design for a foxtoothbrushholder, as shown and described.
FIG. 1 is a front elevational view of the fox toothbrush holder showing my design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a front perspective view thereof; and,
FIG. 8 is a front perspective view with the cover open and showing a toothbrush within the holder.
The broken lines shown in the Figures marking the toothbrush, suction device and internal parts represent portions of fox toothbrush holder that form no part of the claimed design.