I honestly don't know what to do anymore. I went through 20 fish my first month with a variety of water conditioning problems. I finally got the tanks stabilized and now my betta has fin rot pretty bad and my two gold gouramis and my cory catfish have ich. I quarantined my betta alone and cleaned one tank to quarantine the other three alone but now my catfish is dying. Is this due to the ich medicine? Anything I can do....should I quarantine him alone? I think he has ich...he was light green but now very dark and almost black. Any advice?