Ammonia is the big one to worry about but if it was an issue, it would be affecting all three fish, not just the one. Still test for it because it could be that it's a little high but is only noticably affecting the sick fish at this stage.
it really can effect different fish more than others, even of tne same species. I certainly would not rule it out because the other fish look ok. You hit it on the head with the sick fish being effected more though. With rubbing up againt rocks etc it does sound like more of a parasitic thing than ammonia
One thing I would say is key is to get yourself some test kits
Try adding garlic to its food to encourage appetite. It's not a bad all round elixer either. You can get it from some LFS or just cheat like I do and use juices from a jar of minced garlic. I've been doing that for years because I'm a cheapskate.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.