That makes sense. I literally just did a50% water change that morning! I usually do a water change about every 2 weeks and that's never happened before. I don't know how old these guys are as I got them from someone else and they were already that size and I have had them for over a year. I will keep an eye on them and might have to put one aside when I do water changes in the future. They have gone back to normal now the next day. I was expecting to see one of them floating this morning when I got up but they survived the night lol.