"Brown" spot under Clownfish's Mouth

[PlagueisDamask]

Hello,

I've had these two clowns for about a month. Just noticed this spot today and I'm pretty sure it didn't have it before. Does anyone know what this is or how I can treat it?

Thanks in advance!

 

[Big G]

Kinda common bruise. Have you seen it locking mouths fighting? Keep an eye on it. If you see a white filmy area, or redness, or necrosis, it's time for antibiotics.

 

[PlagueisDamask]

I haven't seen it fighting. The spot almost looks like moss. It's kind of "hairy".