The ornamental design for a fluidmixer, as shown and described.
FIG. 1 is a front and right side isometric view of a fluid mixer showing my
new design as seen from the top, the rear and left side isometric view
being identical;
FIG. 2 is a front and right side isometric view as seen from the bottom
thereof, the rear and left side isometric view being identical;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a front elevation view thereof, the rear, right side, and left
side elevation views being identical.