My girl recently died..out of nowhere last week her color really lightened up, she was out much more during the day and had a small cut on her side. To be safe she went into my hospital tank where she immediately latched onto some dirftwood and began to regain color to a dark brown. This morning she was stiff as a board on her side on the bottom. I got her full grown and had her for years, so age is a possibility, but am wondering if this is common? Only one I have had so I am unsure if this behavior is typical while on the way out. Also, all other fish in the tank are fine and water params are right on the money. Any insight is appreciated.