Tank size: 90 gal # of fish: 2 (common+comet) Diet: Mostly Omega One sinking pellets+peas My comet goldfish has some issues with tail. It looks a bit "chewed up" on the bottom (fungal tail rot maybe?). I treated the tank with Melafix and Pimafix about a month ago with no drastic improvements visible. Since then I hoped that the improved water quality might help (so now I do water changes weekly or larger biweekly changes). The bottom of the tail is somewhat better now but then these weird white spots appeared (fungus maybe? cauliflower disease?). They look like little balls growing outside and in couple of spots inside protruding to the outside slightly. They don't look fuzzy to me as in the case of cotton growth. My guess is that the disease affected the comet due to nipping by his tank mate (they are now separated) combined with electric power outage one night which led to raised ammonia and nitrite (nothing too terrible though). Crazy contrast on this one to show the outline of the tail's bottom better. About two weeks ago the second fish developed some spots on his face. First it was just one spot but now there are two. They look white and slightly protruding, but they don't seem fuzzy compared to the cotton growth (maybe it's an early stage of the cotton disease?). My guess is that the fish is rubbing his face on the plexiglass separator which has tiny holes to let the water go through, and maybe that area on the face is irritated or infected now. (The tiny white specks are bubbles) I know this one is out of focus, however you can kind of see the protrusion of the bumps. Water parameters as of today (I use Hagen liquid test) pH: about 7.3 Ammonia 0 Nitrites: 0 Nitrates: 10-15 (hard to tell the difference) When I change the water the nitrates build up to forty-fifty (hard to tell because the color is more saturated in the actual water sample vs. the colors on paper). I usually do 30% water changes using Prime biweekly or whenever I have more time weekly. What kind of the disease could this be? What should I treat the fish with? I looked at the sticky thread with different medications available but many of them are harsh on the nitrification bacteria. I have a spare 10 gal which I could use for a hospital tank but it's small for a 6 inch goldfish. Any help will be greatly appreciated!