Coral beauty problem

[breederforlife]

I got a coral beauty two weeks ago that was quarantined for a week at a friends house. When i got it, the underside of its jaw was all white. Yesterday it had spread and all his mouth was completely white. now today it looks like his lower jaw is gone , you can see his tongue underneath.
I don't know what it is. Is it possible to treat him?
I also have a lemonpeel angel that is completely fine still eating and all.
Do i need to put him down to stop his suffering? I would only do this as a last resort.
thx

 

[MacWilliams]

So is this fish in your QT with other fish? If so what are the inhabitants? Pictures would help as well.

 

[breederforlife]

no the fish is now in my display tank. It developed this white spot about a week ago but it was small and it didn't look like much of a problem.
I probably won't be able to get a picture of it as it is very small and it hides between rocks, but ill try.

The other inhabitants are:
1. a lemonpeel angel
2. a sixline wrasse
3. a sand sifting sea star.
4. a small hermit crab
5. a clam
+ a few corals
Thx

 

[breederforlife]

i got a few pictures, here they are:

 

[HumbleFish]

I can't tell for sure from the pic. Does the white around the mouth look sort of "cauliflower" like? I would look up Lymphocystis, and see if you think it matches.

 

[breederforlife]

No it doesnt look like cauliflower. The lower jaw is just completely gone.
Should i maybe kill him to stop him suffering because his breathing is very heavy, he doesnt eat, doesnt move much. Whats the most humane way to do it?
Thx

 

[HumbleFish]

You could try to treat him with antibiotics in a QT. Something like Furan-2.

This thread discusses how to euthanize a fish.