Keep in mind, it took me several weeks to catch the fish from the original picture. I didn't get him in to the QT till about 3-4 weeks ago. I treated with Furan for sequence...2 treatments with water changes. Now letting him sit and feeding him while in QT. As I said, the tail isn't black any more and appears to be growing back. The dorsal and lower fins are pretty tattered and can't say I see growth yet.I went back and forth on this fish - first I thought it was HLLE, then with the hanging/tattered fin rays, I thought aggression and secondary bacterial infection. Now, with this amount of time having passed and it hasn't either fully recovered or died, I'm not sure what is going on. If it looks improved to you, I would keep it where its at until the fins grow back some more.
He is eating quite well though...full sheet of nori in 1.5 days...