Rolling Goldfish

Question
My problem is that my Goldfish is rolling over on it's side and lying down on the bottom of the tank. It is black gold and white in colour(I know that does not affect the fish itself) and is living with two other goldfish who are fine. Should I take the fish with the problem out or leave it there? I don't know what to do! I have checked the water too and it is fine.

Answer
Aine:  Goldfish can sometimes be aggressive so I would look for signs that the other fish may be picking on your black/gold/white fish.  This may be an issue where it happens only sporadically but causes the fish to try to hide... When fish lay on the gravel and they are not exhibiting signs of disease they are usually trying to hide.  The chief reason fish hide is they feel threatened.  I would put him in another bowl and see if his behavior changes.  If he perks up in a day or two then you will know that he is afraid of the other fish.  If his behavior does not  perk up then please let me know and I will look into this further.  As a precaution I would add aquarium salt to both tanks in case he is getting sick but not yet showing signs.   dave