As i posted in the welcome area those are things you can do as you get more into this hobby, but right now you are concerned about a fish. If you could please post some more info about the tank the size, the water perams what yor feeding them how much what type of fish you have, the names this site is working on a profile section but it noe here now so you will have to go else were to get that info unless you could post pictures. Right noe I would do a 20% water change on the tank, they never hurt unless you take out to much water, Use your water conditioners as you when you do your weekly 20% water change.