I have a koi pond, and my mom added a few goldfish. One of the goldfish had a swim bladder issue when she got it, so she figured she would just give it some peas or something for a few days and it would get better (that’s what the pet store employee told her to do ) so we brought it home, my mom put it in the pond, but now the fish hardly moves and started either getting picked on by the other koi and goldfish or has fin rot, so now it’s quarantined inside. I don’t really know what to do, I’ve never had goldfish before, but I put some sand in my 10 gallon tank, set up the filter with some media from my established 55 gallon tank, planted my largest amazon sword, and gave her a little tea cup to hide in if she wanted. I’ve been feeding her thawed peas, keeping her water clean, and just in general keeping her environment as peaceful as possible. By the way her name is Boop. What else should I be doing?