Watchman Goby with red/white flesh around gills - what is this?

[klimfish]

Hi all, I came home from vacation to a watchman goby in distress. It appears that his flesh on one side of his gills is very red, and around that flesh is even more white and stringy flesh that looks like it is melting away. I have no idea what this is but I have some pictures attached, any ideas?

 

[Deinonych]

What is the history of the fish? When was it added, and was it quarantined? Any recent additions/changes to the tank?

 

[klimfish]

Added the fish about 4 weeks ago now. First inhabitant to be added, I added him with a fire red cleaning shrimp. Drip acclimation, no quarantine. Tank had been fully cycled with spikes in all the right places followed by 0's in all the right places. Cycle had been finished for over 2 weeks before these first inhabitants were added.

I do 50 percent weekly water changes, I'm actually OCD about this tank, it's very very clean. I feed 3-4 times weekly with LRS Nano Frenzy.

Current tank parameters:

Ammonia: 0
Nitrite: 0
Nitrate: 10ppm
Salinity: 1.025
temp-78

There have been 0 fluctuations in Salinity and temperature while I was gone, in fact the one thing that was different over the week is I was away for about 5 days with a friend watching the tank, he has his own saltwater set up that is kicking *** so we went over the details and he know's what he's doing.

It looks to me like a fungus? Or he just got startled and ran into some rock work. Either way his behavior hasn't changed at all, in fact I'd say he's even more active and comfortable with his environment than usual.