Some help please. This is my husband's tank. He is away with work. He did a water change on Sunday, parameter all good yesterday. This morning I fed the fish. Just had a look at them and a female gourami was at the bottom of the tank lying sideways. Loss of colour. I thought I should take her out but by the time I returned she had gone and I saw her floating at the top of the tank upside down. When I tried to take her out I noticed she wasn't dead and trying to right herself. Fins are moving, but she can't stay the correct way up. She has swam around the tank a bit but sideways or upside down. I remember she did have a rather long brown poo attached to her yesterday or the day before for a couple of hours. What could this be? Is there anything I can do?