REEF tank, FISH question

[saltjunkie]

I am sure I already know the answer, but I dont know why?
I have a 50 gallon Reef, lotsa live rock, 200+ pounds of live sand, 12 or so softie , leather corals. open brain, closed brain, shrooms and zoos.
Regal
GS maroon
2 Green Chromis
Yellow head sleeper
all the clean up guys, cuc
snails, crabs
very active fuge.
1.026 sg
80s temp- always has been, always will be so dont say anything about that.
Water changes often enough
Skimmer
Dont ask any water params, what you see is all i check and do.
My sleeper goby is about 3-4 inches long, not very large or cumbersome. He is very active, digs through the sand bed all day everyday. But in the last week or so, hisstomach (lower abdomin area has become caved in.. concave i believe is the word?
He is very very active in the sand bed.
I feed atleast twice a day,
Flake, brine, prime reef, and the frozen algae cubes.
All the other fish are healthy fat active etc.
Could he have depleated the sand bed that completely with as much live rock as i have in there to have destroyed his food source?
Wouldnt he eat all the above prepared foods that fall to the tank bed?
I know once the abdomen gets to this point it is just a slowly dieing fish, i just am curious as to why.. or if the depleted sand bed is the cause?
Any opinions, ideas?

[ClintoninCali]

Sounds like he has an intestinal parasite. They get into their system and take all of the nourishment from the food and the poor fish starves to death. I've seen it in a few anthias before but they didn't last long. They stayed really active until the day they died. They looked like they lost their appetite though the last few days I remember. Hope he pulls through.

[saltjunkie]

i hope he makes it... thanks!