Help

[bmcnicol]

My yellow watchman goby has a small purple-grayish patch on one side of it, and i have no idea what it is. I'm trying to get a picture of it but i cant get anything clear. Please tell me what it is and if i should worry.

[aynoT79]

Hard to tell what it is with no pic.. Maybe he/she could have scratched itself on a rock, i have had fish do this before...