I have an at least eight-year-old comet goldfish that - well - hasn't been looking her best, to say the least, since we put her in a twenty gallon tank. Her first symptom was cloudy eye, but she's gotten much, much worse since we noticed it about a week ago. Along with the eyes, she has some strange, fluffy, white, fungus-things growing all over her. They're not very visible until you turn on the aquarium light, then ... hoo boy ... icky. Along with that, her tail almost seems to be decaying, it used to be very long but the - webbing, I'm inclined to call it - is disappearing, and there are red marks on her as well, mainly near her fins. I also noticed that she seems to have a sort of tumour on one side of her body, like half of her is bloated and half isn't. She's kind of swimming around near the surface of the water gasping for air, she's vertical most of the time. Am I right to assume there's no saving her? I tried very hard at first, I went to a special fish store to figure out what was wrong and they said to put her back in the ten gallon tank and gave me a treatment for the water in her old tank along with some medication, but she's been getting progressively worse and I've been thinking that euthanasia could be the kindest thing for her. And if all hope is indeed lost, what would the most humane way be to euthanize her?