Help for yellow watchman goby?

[impur]

I have a yellow watchman goby in my 10 gal nano. He has been in the tank about 2 weeks. I noticed the other day that a small area on his back, behind his head and right in front of his dorsal fin, has turned white. I also saw him rub on the sand and rock last night, although this is the first time i have seen him do the scratching. He is still eating and looks fine otherwise. I tested all parameters except calcium and carbonate hardness and all levels are fine, in fact i think the water is in the best condition since the tank was set up. This is the only fish in the tank. Could this be a vitamin deficiency or something? I feed every other day. The foods i alternate with are flake, frozen mysis soaked in Kent Zoe, frozen brine soaked in Zoe, Kent Phyto (i know this is not for fish), shrimp pellets. I hope someone here will be able to help me out, reefcentral and nano-reef.com haven't been much help.

Sean if you read this its the same goby i got from you. He has been perfectly healthy, except for the white area. Ever run into this?

[impur]

pics

[impur]

This morning the white has extended down his side. It is not raised, nor does it look like something sloughing off. It doesn't look like a disease, just like the pigment in his skin is changing from yellow to white. The only thing i can think of is maybe he has been getting scared by my emerald crab and wedging himself in a little area where his cave meets the substrate and the top of his body is against the rock. But i'm not so sure this would cause his skin to change color. Anyways, i would greatly appreaciate any input you may have.

Miles