So I’ve had my diamond goby pretty much the whole time I’ve had my tank. Like 4 months. But I’ve never noticed this before. However, I’ve seen a few pictures of them like this. It’s like a reddish bluish spot near his head. It almost looks like a bruise??? Also he’s been eating normal but not cleaning like normal. Normally he keeps his sand spotless but it’s been getting dirty looking lately. Is he okay?? I’m attaching a picture but it’s not the best picture ever.