White horn of clownfish

[Lil reef]

Hey, I noticed tonight my male clown (part of a pair) appears to have front white protrusion coming out of his top fin. Was thinking it might be bone after fin damage, but It appears to be in front of the fin like a horn. Anyone have any ideas what this might be?

 

[P-Dub]

Percunicorn.

 

[cshouston]

Exposed dorsal fin ray. It likely suffered some tissue damage either from aggression, an accidental injury, or potentially a water quality issue. What else is in the tank, and what are your water parameters? The tissue can grow back, but keep an eye out for secondary infection.