Knowing how badly I don't want to put these fish down, my husband has suggested I put them into an empty glass box. A completly bare tank with nothing but them and water.
Bleach their old tank to kill anything that is in it. Give them as many water changes as needed to allow them to exist for a while in an unfiltered tank. Daily 75% if needed. Add any meds I fee appropriate (although I don't know what else to try).
That would kill what ever is in the tank, and maybe allow the fish one more chance to beat this. They are both quite active and act like nothing is wrong.
What does anyone think of this plan?
I can pull a spare filter off another tank so that they can go back into a cycled tank when they are ready.