I wouldn't do firemouths with either of those fish in a 65g. Firemouths for the most part are all bluff. I don't know that a firemouth would be able to cope with the abuse that a GT or Festae can dish out. That isn't to say that it can't work. Given plenty of caves and breaking of sight lines it may work out perfectly well. Good luck with whatever you choose. Make sure that you post pics once you get it up and running.
