Do parasites/fungus/bacteria preferentially attack rays as opposed to clear parts?

[mrfishes]

Do parasites/fungus/bacteria preferentially attack rays as opposed to clear parts? I'm asking because I have white spots on rays of the tail...not on the clear parts of the tail, or anywhere else on the body. Does this ray-only location indicate mechanical damage? Or do parasites/fungus/bacteria preferentially attack rays as opposed to clear parts?

I posted another thread this morning on the spot issue, but this is a new, more specific question I'm posting here.

[jpdevol]

In my experience the spots - or growths - on the fin spines are often caused by physical injury. I am not aware of a specific bacteria or pathogen that work on spines vs fin tissue.