I use to think the same thing.  I have 12 that live in a room.  I use to
say as I added one it.  Get it out your system and get along.  And it
worked.  That was a year ago.  Now they don't want anyone else in there.
I put one in there last week.  Boy, I didn't know what was going on, I
saw the ferret with 3 on his back.  Then I had to put my hands down
there.  I will be putting that ferret who is already very aggressive in
there in a big cage.  Maybe the scent thing and familiarity will work.
 
Some of the ferrets that I have rehabbed for the Ferret Business of
Georgia, just don't and won't get along with others.  But, when you are
rehabbing why stress them anymore.
 
There are some ferrets that are scared of other ferrets.  Who knows what
actually has happened with ferrets before they come to a shelter.  They
just don't like other ones.
 
Just never know why sometimes.  They actually want to really hurt another
ferret when it is around them or on sight of another.  I had one ferret
jet across the room to hurt another one.  Caught him right before the act.
 
I use to think it was uncommon.  Now I don't
 
Benita
[Posted in FML issue 3902]