Still taking care of the tank at an elementary school and today I noticed that one of my plecos has a bald spot on him and he isn't being very active..just kind of hanging out near the bottom and not swimming around much. I have 2 plecos, both of which are very active and swim around the tank. The other one seems fine, but just today this one is near the bottom not swimming or moving very much at all and it looks like he has a bald spot on him. I called the pet store, they have no clue what it could be. Over a week ago the power went out at the school for over 6 hours, I lost two of my black skirt tetras, the other 2 black skirt tetras seemed fine and the 2 plecos seemed fine until the one today. Does anyone have ANY clue what this could be or what to do for the poor pleco? The plecos don't fight, the majority of the time they're laying next to eachother on the glass or a tank decoration, it's really cute, so I don't think fighting or sucking on eachother is an issue. I also feed them algae wafers which they love. The water has tested fine and I cleaned the gravel and did a water change just a few days ago and the water still tests fine. Any help is much appreciated!