Clownfish w/beard: fungus? something else?

I have two true percula clownfish as the only fish in my new 75G tank with 
90 Lbs LR.  They've been in for about a week.  They have been doing well, 
came back from Thanksgiving holiday to notice that the smaller one has 
developed a whitish "beard" around (espc. below) his mouth, looking perhaps 
like it is going into his mouth.  His mouth is not clear, certainly, and it 
looks like  perhaps his mouth is not closing all the way.  Any ideas if 
this is some kind of fungus, or something normal, or something else?  He's 
still swimming and going after food, but I'm concerned about the future...  
Top fin (dorsal fin?) is not up as much as the other, which makes me think 
he's a little under the weather.  The other fish looks fine.

So:  any ideas what this is?  And suggestions on what to do?  Quarantine?  
Freshwater dip?  Try to pull/scrape the object off with tweezers?  I've 
read some FAQs on clownfish diseases at 
http://www.wetwebmedia.com/clnidfaqs.htm but didn't see exactly this 
problem described...

Oh, the water seems OK as to quality, 0 ammonia, 0 nitrite, <10 nitrate 
(lower than I can pick out a value given my test kit), 8.2 PH, 1.026 SG, 
running protein skimmer and power filter.

Thanks!