I have a couple of oak barrel fountains and I have inserted the molded
plastic liners to keep them from leaking. These work great, but I
don't like the way look, I would like to find a flexible sealant that I
can brush or spray on the inside of the barrel. There is a catch; I
would also like to be able to put fish in the fountain, so nothing
toxic.

Anyone have any ideas?

Thanks!
Steve