Single White Stringy Growth on Tang Fin

[_HULK_]

My tang (whitetail bristle tooth tang) has a stringy white growth on its right fin. I first noticed it as a small white dot a few weeks back and since the tang went through QT months ago I didn't think much of it other than maybe some debris that got stuck to it. Now its grown into a string, its been in the same spot, hasn't moved and no visible signs anywhere else on the fish.

Tank Inhabitants when I first noticed it as a dot:
All were QT'd prior to adding

Rock Flower Anemone
Snails
A couple of LPS/SPS

Tank Inhabitants now:
All QT'd as well
Same as above plus

Royal gramma
Fairy wrasse
Chestnut blenny


My QT procedure
I QT no more than 2 fish at a time and have a separate QT for inverts
Observation 1 week (didnt notice any ich, brook, velvet) tang was really young when purchased
Cautionary Treatment included kanaplex, metroplex slightly longer than the recommended length
During this 2/3 week period I converted truly freshwater balloon black mollies (three of them all are still alive and were recently retired to my cousins freshwater tank)
With black mollies and tang in QT I dedicated 20 min during the day and night to see if I noticed any weird behavior, nothing.
During this time the tang seemed fine, better than fine actually and the mollies showed no sign of disease.
Total time in QT 6 weeks +/- a day or two
Total time in display three moths

Diet includes
Nori
tank algae
blood worms
meaty food cubes

Assuming this isn't flukes, brook, hookworms etc. Is it possible (waky theory incoming) that the UV setting on my light is too high causing abnormal growth? I would think not since they are getting pelted with constant UV in the wild.

 

[KrisReef]

I reject your wacky theory based upon your own description as i unsderstand it.

I do think it is an external paracyte, based upon your pictures but I cannot go further to provide any diagnosis. I'm replying to bump this along and see if others recognize your situation. A clearer picture might help. If you could net the fish and put is in a small tank, or take a photo while you hold the fish in your hand, either might be helpful to get a clearer view of the question. hth.

 

[_HULK_]

So here's a quick update, its def. a worm/parasite of some sort. After becoming that string you see in the photo it moved to the underside of the fin and now its on the opposite side of the fish (over three days). I'm researching options on how I can treat the display tank cause where there's one there's more.

 

[Jay Hemdal Verified Community Expert]

Sorry, I missed your first post. Can you get a clearer picture taken under white/natural light?
This could be the egg case of a parasitic copepod, but it just isn’t clear enough of a photo to say for sure.
Jay

 

[_HULK_]

Unfortunately I can’t cause the casing is gone now. If it comes back I can definitely do that.