I had two gold fishes and a few days ago I noticed my other fish was sitting at the bottom of his tank and struggling to to get to the top (swimming to the top and automatically sinking down). I had no idea what was wrong because he wasn’t acting that way the day before, so I panicked and did a full water change thinking it might improve and after my fish being in the water for a few hours he was still sitting on the bottom until he died.
My other fish now has a wound on the top of his head and I’m not sure what it’s from; all help is appreciated.
