When ferts play it can be very vicious.  Especially when they are breeding.
We have 14 ferts right now.  We had to get a pet shop license because we
have so many.  Usually when they have a grudge against one or another it
may take time for the pay back.  You have to let them duke it out or it
will continue later.  You have to montor he fight but they will play with
each other again.  We have 2 brothers from different litters, Sasquatch
( 6 toed polydactil) and Gator that would not get along.  We tried Bitter
Apple and everything else we could think of.  Even washing the sent to make
it the same.  Finally we just had to let them duke it out.  Now they are
OK.  They still duke it out once in a while.  They sleep togeather but
won't play yet.
[Posted in FML issue 3269]