Your fish hate you. There "was" nothing wrong with that copperband, but there is now unfortunately.
I am not sure why I have been putting fish into my natural tank for over 40 years and never once had to medicate or dip in anything. I think that copperband in a natural tank would be eating and putting on weight and in a week would be looking for a date.
We never think about the fishes state of mind. We need to read their mind and they are easy to read, look into their eyes, even though they have small eyes.
Remember, they can see you, they can see your living room, look out your door and see the nerdy looking guy across the street washing his car. They see all those open spaces in your home but they can't get there.
A copperband especially needs real hiding places in real rock with real copperband food, not bloodworms which are freshwater anglefish food.
That fish would flourish in a natural tank and there would be no needs for medications of any kind. All I have is Alka Seltzer, but that is for me when I disagree with Humblefish even though we love each other. In a very Manly sore of fishy way.
I'm only giving you a thumbs up because I love the way you and Humblefish bicker back and forth. You're kind of like the Odd Couple. Good thing you love each other (in a manly way). Keep at it; it makes my day. [emoji225]