In case you don't see this in another response, I wanted to pass along an idea that helped my fancies' convalescence- I have lost some of my big fancies when I have moved them to a separate hospital tank - different environment, size, water environment- who knows why. I found these little plastic baskets for a $1.00 (dollar tree) - they float in the tank, ,are large enough to give the isolated fish plenty of room, they couldn't see her, I could see her through the little handles and it allowed continuous clean temperature stable water exchange as it floated and the water entered and exited the handle openings (so it works for tropicals and fancies). I kept my hurt ryuykin in one for days and have since used them for hatching and raising pleco fry in the main tank (just added an air stone for agitation) and even isolated fish needing medication by reducing the amount of water in the basket below the handles so the basket floats higher and fish and meds stay in the basket without affecting the other fish or the tank. They come in various sizes as well. Hope this helps!