Hi, one of my Threadfin Rainbows is showing signs of swimbladder issues (barrel rolling, upside down etc) I am aware that this can be treated if it's bacterial but can it be treated if it is caused by a lowering of temperature? I think it's this as I did a w/c on the tank yesterday and the temp did drop by 3 or 4 degrees which is far more than I usually get (the water must have been exceptionally cold from the mains last night!). The fish in question has only been i the tank for a few weeks and was slightly weaker than the others anyway.