Ok I think my dad's right... google 'parasitic isopod on tang' and have a look at the images that come up. Also found these cases on Wet Web Media under Isopod Control:
I have a powder brown tang which has picked up a quarter of an inch long light brown crustacean on its anal fin. The bug looks kind of like a terrestrial rolly poly or pill bug. Also this thing seems to be pinching the fin. I already have a cleaner wrasse and shrimp. Do you know what this thing is and if and how I should get rid of it? I bought your book this weekend and there the bug was right on page 148. Also I have a white faced tang and I now feel pretty bad about buying that cleaner wrasse. Anyway the copepod disappeared after about 8 hours so I assume the cleaners got it. I am glad I bought your book. It answered a lot of questions and gave me a lot of ideas. Thanks for your time and Ill investigate further before submitting a question. Everett West >> Yes, this is a parasitic isopod... an aquatic type of rolly poly... and it is best to remove it by catching the fish and prising it off with a stout tweezers... Get ready and at the same time, daub a little mercurochrome or Merthiolate on the remaining sore with a "q-tip"... Bob Fenner
Isolating Isopods Hi JasonC, Good job filling in for Bob. <<why thank you... >> Can you give me some advice. I have a Sailfin tang with a parasite hanging on to its bottom fin. I'm pretty sure the parasite came in on a piece of liverock, but regardless its there. The thing looks like a white worm. Maybe 1/16 of a inch long and 1/32 of an inch thick. Pretty small but large enough to see some features on the parasite. I first noticed it about 2 weeks ago, and since it has doubled in size. There is now a small hole developing in the fin where the things mouth is. The tang does not show any signs that he is distressed yet, but I am afraid of letting this thing get to big, or if it reproduces god help me. I have a cleaner shrimp that cleans the tang from time to time, but the shrimp never touches this fin. I waited these two weeks hoping the shrimp would get it, but to no avail. Do you suggest a neon goby or cleaner wrasse to be added to the tank? If I could catch the tang (yeah right), would a fresh water dip be a better option? Would scraping it off with my nail work again if I could catch the tang. Last night I did notice 2 tiny white dots on another fin. I'm afraid these are small versions of the same parasite. <<Two courses of action here that I can think of, and both will require you to catch the fish. You can either manually remove the isopod, either with your fingers or tweezers OR freshwater dip it off - either one will work - the manual method will probably be quickest with the lowest trauma to the fish. Doubt the small dots you are seeing are the same thing, but if you've got one, you could have two... keep your eye on it.>> Thanks Mike T <<Cheers, J -- >>
I haven't done heaps of research on this so by all means look for other options, but looks like you may have to wait till its on the fish again before you can remove it based on the advice I have found online...