I’m unsure what is going on and hope I can get some help.
Context:
Carnival goldfish about 2 years old.
I’ve been taking care of it the last year.
Tank size I know is too small but it’s 18-20 gal.
I missed some water changes over winter and did a big water change a few weeks ago. Put in fresh charcoal in the filter, rinsed all the media and sponges in old water. Fish was doing well up until about a week ago when this film/growth started spreading. Now he’s very lethargic.
I took a water sample to a local store for tests. Pneumonia levels were on the higher side which is probably to be expected. They said nitrates (edit: it may have been nitrites. The test was a dark green color.) were high as well, which I didn’t expect. They said to do some water changes and start using Prime everyday and come back in a week for another test.
As far as what’s actually on the fish they were unsure but said it probably wasn’t ich or the other common one. Main guy there said my fish is probably experiencing a disease due to high levels of stress. The fish has been fine and his normal self up until this last water change and even a few days after. Very active, plopping the water during feeding times and such.
Any help would be greatly appreciated. Obvious things like bigger tank are not immediately available at this moment. Thank you!