He was just fine this morning. Although I did notice a perfect little tear in his tail. Like it was cut in the middle. Went to the store, then I noticed he was just staying in one spot, and kind of wobbling.(Don't know how to describe it.) And his tail looked almost shredded. It looked like someone cut it almost into fringe. Then he darted to the bottom of the tank head first and layed there on his side. Then he would try to swim up and do it again. 'Til he died. Could this have been fin rot? Or maybe the other guppies?