He's not playing in the flow :-( He's trying to get the Ich/cuticle off. We have alternating flow, and every 5 min-ish, the flow would switch and the Ich infested Volitans would swim over to the other one. This is one of the first thing I notice with Ich when all else looks well.... they sit in front of the flow and they shed alot.
Have you ever seen my feeding stick? There is ZERO chance of injury to ANYONE using that method. Lions may not be aggressive, but mistakes happen and a hand fed lion is a risk for a poke. Eating is important right now. It can encourage a shed and that will reduce the numbers on him.
If he won't take a varied frozen diet right now, I would get some ghosties and load them up with a bunch of enrichments. I can't speak enough about the importance of tip top nutrition when dealing with such things.
I would not bring this issue over to the new tank. If anything, I might get that one ready and use the current 55 as a QT... it could still go that way. Moving him around now would absolutely be the worse thing for him unless it's out to a tank for a hyposaline treatment.
I'm honestly not really liking the angel with him, and IMO that could be a source of stress. You don't have to see it for it to be there. But, I'm not the Tankmates Police
Vitamin C boosts immunity, so if you are unable to do the Beta Glucan right now, I would add Vitamin C to the tank water. There's hobby preparations out there, but you can also use Human grade drug store stuff. I've never used that form, so you'd have to read about that elsewhere. I've been using vitamin C for ailed fish, and I have noticed a HUGE improvement.
But if something is still stressing him, this could be moot. Ya gotta find the source of the stress.