Can a fish break it's fin?

[fishoholic]

My scooter blenny wasn't looking to good today, laying on his side barley moving. Thought he was dying but couldn't figure out why as he's been eating well (eats frozen mysis) is fat and seemed fine yesterday. After awhile I had thought he died but when I went to scoop him up he darted away.

I watched him closely and he was laying on his right side spinning in circles not moving his right fin at all. His fin is completely in tact (my first thought was maybe it got nipped or torn or was partly missing) however he's just laying on it not moving it. So I'm wondering if it's broken????

Here's a pic (kinda hard to tell but it was the best pic I could get)