It's not the typical passing either that I usually hear from a fish rescue.
I had gotten Gill, a halfmoon plakat half giant (king), because he was a 20 dollar fish that slowly digressed in the small cups that couldn't hold his size. I got him one day after noticing the amount of ammonia that was in his cup and how he barely moved.
It took a few days but I got him well enough that his colors came out, his fins were no longer clamped, and he went from being a timid fish that ran away from my hand no matter what, to a fish who raced up for me to hand feed.
I had given him to someone since I didn't intend to keep him. The person in question was asking all sorts of questions as how to take care of him so I felt it was reliable. She dropped it off at her fathers with directions so she could come back the next day (during move out at a college). Only to find out that he hadn't put in any water conditioner in his water. She got some right away but he had already been in non-conditioned water for a long time and the effects were already taking place.
Least to say, he didn't make it.
We talked some about what do to in the future if she decided to get another fish and she was extremely apologetic. I'm not mad at her, but I am a bit upset.
I think next time, if I want to do a rescue, I'm going to make sure I can keep him first. I don't know. This has really shaken me because I saw how his personality was brought out by the time he was doing extremely well in my tank before I gave him away. I almost changed my mind when she came to pick him up.