Hi, I'm not sure of you still have him or not but if you do I have a few questions.
#1. In the video, was that his tank or did you move him to a smaller bucket for treatment?
#2. How often do you change his water, and how much do you change?
#3. Does he share the 610 with any other fish? If so what else is in there with him?
Assuming you still have him preform a large water change, take out and replace at least 350 gallons of his water, better if you can change 450+. Do this every day or every other day until you see an improvement, everyday is better.
Good luck.