Blue Damsel In Distress

[Queen Bee]

Yesterday all was well. Came home tonight and the larger of the 2 damsels in the tank looks like his lips were bitten off. There is also a discolouration on the back half of the fish. Pale blue to almost white. The other damsel and 2 clown fish are fine and acting normal. Is it mouth rot, fighting or maybe something else. Pics are not clear as the fish kept avoiding me and swimming back and forth at the back of the tank. The tank has coral, hermit crab and live rock.

I have a yellow watchman gobie and pistol shrimp in a quarantine tank. Been there for about 2 - 3 weeks. They are fine.

Should I move quarantined fish to main tank and put sick damsel in quarantine? Should I medicate the main tank?

 

[Queen Bee]

Just peeked in tank, damsel no longer swimming kind of just hanging out. Discoloured back end is now almost white and has a large marble size lump!!

anyone know what to do or where else I can look??

 

[bae1994]

what are the other fish in the tank

 

[Queen Bee]

what are the other fish in the tank

2 clown fish, a red leg hermit crab, and a smaller blue damsel

 

[bae1994]

im really not that sure tbh it almost looks like a heater burn but im sure some one may help

 

[Queen Bee]

Just got home. Damsel has died.