Dimino damsel not eating

[cells]

one of my domino scratched his face against the LR like 5 days ago. This morning it stopped eating. there is also a small white growth at the tip of his mouth, on the upper lip. He is still active and lively, but stopped eating this morning.
Is there any suggestion on how to treat it? Can I do anything to help with the scratches on his face?
Thanks.

 

[simm]

Just leave him and keep an eye on him. If he gets worst or others pick on him Id put him in a QT tank!!

 

[cells]

Thanks simm,
how to set up a QT tank?
how big must it be? need any filtration in there? How long should a QT period be?

 

[simm]

For small fish a 10 gallon would work. Just a heater a small filter and something for them to hide in. Let the tank cycle first. QT period maybe a couple of weeks depending on if the fish is getting better.