Recently I noticed this red coloring on the tips of 2 of my fish’s dorsal fins. They’re in different tanks and eat different food. My third fish doesn’t any changes. I took a photo of my tiny female fish Eleanor in lighting that shows the discoloration. My adult male won’t let me get a good photo of his fin. We have well water but this change only started about a week ago. I’m attaching a photo of my tiny female Eleanor. Any ideas how this happened?