Comment 1 for bug 1464487

I also have this problem. I was originally using gnome on this system and catfish opened files/nautilus. I then installed Thunar and uninstalled Nautilus. That's when Catfish started opening Audacious. I uninstalled Audacious and now it opens baobab.

I was having this problem with other apps after removing nautilus, but edited:

~/.local/share/applications

and added

inode/directory=thunar.desktop

Other apps seem to honor this, but catfish doesn't. It also ignores the xfce4 preffered applications setting and the MIME type editor settings.