My male Odessa Barb which I have had for a little over a year has started to swim upside down and his tail fin looks in rough shape. He also looked like he was coughing up some kind of white powder or something. I had a Betta in there that ended up with dropsy a couple months back, he was removed and ended up dying. The Barb now also has a swollen belly. Water parameters are good. The tank has been cycled for well over a year now. It's not overstocked.