Clown, Black Percula missing tail. Certain death?

[ner'T']

I came home and my clown was missing its tail... just a ratty stump left. It can still swim better then you'd expect.

Yesterday I found it in the middle camber on top of the filter pad. I moved it back and it seemed fine.

I unplugged the Hydor Koralia to mellow out the currents.

I'll try to get a photo

Any suggestions?, or experience with major fin injuries?

-Biocube Tk
-only fish in tank