Invert/fish disease transfer

[Fishnut]

Has anyone had any experiences with Inverts introducing a disease to a tank of fish?  I won't be adding the water from the fish bag because I've got the critters in a temp tank.  It's not really an appropriate place to keep them, so I was hoping to move them to their new home sooner than my 6 week quarantine period is over.

I got 2 Mexican Dwarf Crayfish.  They both went in the same bag for the trip home and by the time I got there, one had ripped several legs off the other...sheesh.  They're each in a large jar that I usually reserve for bettas.

Here's a pic that I found on-line that's pretty close to what mine look like: