Diamond Goby Spot

[Bear Claw]

Ive recently noticed that my diamond goby has a big brown circle under his chin. Is that normal?

 

[blaxsun]

Upload a few images under white lighting and I'm sure the resident goby experts can weigh-in.

 

[i cant think]

Ive recently noticed that my diamond goby has a big brown circle under his chin. Is that normal?

Photos?
To me it sounds like a male/female type of deal however I can’t be completely sure without a photo.

 

[Bear Claw]

Got it! I will when the lights come on in my tank