Hi I am a new addition to this website. I have a 10 year old goldfish that is living in a 20 gallon high tank. Routinely it develops updide down wsyndrome. I have tried antibiotics, feeding peas and sea weed, adding epsom salts to the water but she still goes belly up on occasion. I am wondering if there is anything I am doing wrong. I know that keeping a 10 inch fish in a 20 gallon tank is not optimal but she oulived all the other tank mates and appears to be happy. (a larger tank is out of the question since I live in an old apartment and dont' think that the floors could hold tha additional weight of a larger tank. Any suggestions would be greatly appreciated.................