No problem, I hope you can figure it out. If you bought the fish locally, maybe see if you can trade him for one that's not " defective".. Lol
I had this happen to me once with a clown, he was fine other than the obvious problem, and seeing that he looked OK still, they let me trade him.
holding tanks are so small usually that picking up on something like this at the store is difficult at best, they always seem up and down at the glass. It's not until you get them in larger tanks, with some horizontal swimming room, that you see they can't really swim horizontally!!
Again, best of luck!