Hey all, just a quick question that has been on my mind for awhile now. But first, here is some background information. So when I got my larger 75 litre cold water tank I took on my boyfriends four danios because his parents didn't want them anymore. They didn't clean their tank for months because they wanted them to die. Anyway, a month ago I lost one due to his age. All of the danios are between 5 and 6 years old. He showed signs of death as he stopped eating and lost his buoyancy completely. Now, for the past week, one of the other danios is doing the exact same thing. I know he will pass very soon, and I don't want him to die in agony like the last one. Therefore euthanizing him has been on my mind. I have had to euthanize fish before, although that was because of a severe case of dropsy. Before I make a decision I would just like some input on what I should do and what is best for the fishes welfare. Also, I forgot to mention that this is a two part question... All of my danios are showing fluffy sort of spots and so is one of my white clouds, except his isn't on a fin and instead is on his belly (I will try and get pictures on the morning). One of my fish keeper friends said to try fungus and fin rot treatment, however I also need to treat my goldfish, Dot, with his unknown condition. I plan on treating him with anti parasite stuff because he has some symptoms. Anyway, my question is, is it okay to treat the two at the same time? If not then which one should I treat first?