I have a goldfish in my water garden and it's forever upside down. It swims for a little while the correct way then it's either facing down with it's tail up or upside down. Should I be worried about this.

Sounds weird, but I found this same answer at multiple websites:

http://www.answerbag.com/q_view.php/4149


EDIT: Here's some more detailed info: http://www.koivet.com/html/articles/articles_details.php?article_id=149&category=17&name=Diseases