Copy over /usr/share/applications/feh.desktop
to ~/.local/share/applications/
and change the Exec=
to match what is shown below.
[Desktop Entry]
Name=Feh
Name[fr_FR]=Feh
Name[de_DE]=Feh
GenericName=Image viewer
GenericName[fr_FR]=Visualisateur d'image
GenericName[de_DE]=Bildbetrachter
Comment=Image viewer
Comment[fr_FR]=Visualisateur d'image
Comment[de_DE]=Bildbetrachter
Exec=feh --scale-down --auto-zoom %F
Icon=image-viewer
Type=Application
StartupNotify=false
NoDisplay=true
Hidden=false
Terminal=false
Categories=Graphics;Viewer;
MimeType=image/jpeg;image/png;image/gif;image/tiff;image/bmp;image/x-icon;image/x-xpixmap;image/x-xbitmap;
Now, when you double-click on an image in Thunar, it should open with feh --scale-down --auto-zoom
.