lump on tang fin

[nlandgraf]

My sailfin tang has a large lump at the base of his left fin. I will try to post a picture later when I get home, but any ideas what it could be without the pic? The bulge is about the size of a BB, maybe slightly larger and sticks out from both ends of the base of the fin. There are no other abnormal markings anywhere on him, and his behavior has not changed at all.

 

[RBU1]

lymph is it white and cotton like?

 

[nlandgraf]

Here is the best picture I could get of the tang. The lump is the spot right at the base of his fin & it looks a little worse on the other side of his fin, against the body. No other markings on him though.

 

[nlandgraf]

any ideas?