We have had interesting experiences with ferrets and aquariums. The ferrets seem oblivious to the fish, but love the charcoal bags in the filters we use. We use the basket type filter and unless we tape down the lids, the ferrets open the top and pull out the charcoal bags and proceed to spread the charcoal everywhere they can manage. On the lighter side, we had a beautiful set of black ferret foot prints marching across a futon cover once thanks to this. Mike, Erica, Ian, Inigo, Buttercup, ... [Posted in FML issue 0606]