wrote...
Well, after ongoing long-term attrition, my remaining ADF is all by
hisself.
Now I have to decide if he's better off by hisself, or if I should get him
more ADFs to hang out with?

Are there "territory" issues introducing ADFs into a tank with existing
ADFs?

Will he be ok by hisself, or is it important to his well being that he
have
buddies?

six one way, half-dozen the other. they are resilient little guys that in
my experience work well alone or in large groups in a single tank.
personally i keep at least two together, untill after a few months of
watching i become convinced one has died and add what ends up being a third.
;-)