Last night I discovered that one of my female guppie's fin was slightly white on one side, and in 24 hours it got from a showcase guppy to this halved-fin guppy on the pics. I had to remove it from my tank, but I also noticed that most of my adult female guppies showed similar symptoms today. And it only happened to female guppies! How is this possible? I didn't really notice any fin nipping going on in the tank!