Now it is a wait and see game I guess.
Yesterday I set up his bubbler as soon as I was told it did not absolutely need the ball valve. He was SO HAPPY to see the bubbles. I'm not sure if he has ever had such a thing in his 15 years. He plays in them, swims in them, lets the bubbles carry him up and then goes back down to do it again

The current the 206 creates in the small 20 gallons is not too much for him- I am watching to see if it tires him. He seems to enjoy it and I felt it with my hand-it is mild. I have a large sponge ready to go over and dampen the outflow valve if it appears it tires him and he doesn't like the current after awhile.
This would be his fourth day with me and his eyes appear yet better again today-less swollen. The first day I found him suffering in that bucket the lenses were so edematous they would billow in and out with his body motion as he swam. All of that is gone now-their swelling keeps decreasing. He may need to see the vet once firmly stabilized as I was reading about pop-eye (if that's what it is) and he likely has a bacterial component.
I still have 24 hours to go of holding feedings before I am supposed to attempt giving him a night crawler. That is good- it will give him today to adapt to his new filter. He is passing waste. I took a picture of some this morning- I have seen clear to white long strings in the tank but this morning I also something more brown looking- I photographed it in case its important and tells anything key about his health status.
His behavior right now is promising-active, playful, curious

I love Fluval products. They are well engineered. The other filters they sell in pet stores are complete garbage and a joke-its absolutely worth it to spend the money and get a good Fluval filter.
I have put my life on hold for 2-3 days struggling to learn what he is, how to stabilize him and get him into what I feel is a safe set up. Today I feel like we have reached an appropriate level of safety so that this is no longer at dire emergency level- with that filter in place he now has a fighting chance to survive. I will just have to wait and continue to do my best.
I will post pictures and an update this evening. I am trying to use my better camera to photograph him so you can see his eyes in better detail, the one I use to photograph my jewelry (I am a jewelry artisan). But capturing a moving subject under water is tricky. Its a pretty good SLR digital camera with lots of settings so maybe eventually I can get it.
Thank you so much Racoll, Birger and everyone else who has helped me stabilize him. I can finally exhale now. An endangered fish being kept in only a container of water is a real emergency. Now he has a decent set up-maybe he can survive. Time to work really hard and try to earn back all the money I just spent!