I would really invest the money to get a good liquid test kit and test your water parameters, since you have stated previously you've never tested your water before. That fish looks in pretty bad shape, I have never heard of something like this appearing as you said --- that it "was spotless one hour before" the photo was taken, looked like that, and then less than twelve hours later it is "almost gone". Sorry, I just have a lot of trouble believing that, I have never heard of or seen a fish look absolutely fine, then look like it has a terrible, far-gone case of ich, and then look all better, all within a 24 hour period.
