The ornamental design for a petfountainbasin, as shown and described.
FIG. 1 is a top-front-right perspective view of a pet fountain basin showing my new design;
FIG. 2 is a bottom-rear-left perspective view thereof;
FIG. 3 is a front elevation view thereof, the rear elevation view being a mirror image thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a right-side elevation view thereof, the left-side elevation view being a mirror image thereof; and
FIG. 7 is a top-front perspective view thereof, but shown in an environmental view with a reservoir and water pump nozzles; and,
FIG. 8 is a front elevational view of FIG. 7 thereof, but shown with the reservoir removed to show interior hoses and a water pump.
The broken lines showing of the water pump nozzles and the reservoir at the bottom in FIG. 7, and the hoses and the water pump in FIG. 8 are included for the purpose of showing environmental structure and form no part of the claimed design.