I appreciate the response. Would not the other 5 rainbows be infected as well?
I wouldn't want to risk the main tank so if the choice is euthanizing them or just keeping them in this tank, I guess I'll keep in the QT indefinitely. I'm not good with euthanizing (I probably need to euthanize the female rainbow in the other thread that has swim bladder, but she's still sitting in the bucket).
I am leaning towards it having been an injury though as it did seem to appear out of nowhere. They had been in the QT tank for 1.5 years without any new fish being introduced. Out of the fish that were in QT with it, four of them were put in the main tank about a year ago. Rummynose died b/c i overdosed Safe in the other 10g I had moved them too. Other than that, the only other issue was a female praecox that had prolapse and was underweight and died when I started adding salt, and a female that had a slight swim bladder issue that healed.
