Yellow Tang Digging Holes

[kmbyrnes]

Just got back from an extended vacation. My son did the feeding and I hired the maintenance out to a great tank guy. Very happy with him.
Since I got home10 days ago, I notice my yellow tang has been 'finning' the sand bed endlessly. What used to be a nice smooth white plain now looks like Olympic moguls.
She is constantly whipping at the bed with either tail of fins, then poking around for tasty morsels.She shouldn't be hungry. She gets a 2x2 sheet of Nori daily, plus the tank is overfed due to my Anthias.
I've had her for almost 9 months and never seen this before.
Any ideas?

Water Params:
Temp 81.5 - I live in AZ !
Salinity 1.025
pH 8
NH3 0
NO2 0
NO3 0
PO4 1
Alk (dkh) 10
Ca 480
Mg 1360

 

[Washout]

I am no tang expert, but as weird as it sounds in an aquarium it almost sounds like she's building a nest.

 

[Dmorty217]

Is the tang "fanning" the sand or "scratching" the sand? With you being on vacation I would think it's the latter. Usually people come home for find sick and diseased fish

 

[kmbyrnes]

Thanks for the replies.

Washout, that's an idea but why all over the tank?

Dmorty217, I have had sick fish previously and seen them rub and scratch their sides on rocks and other things in the tank.
This is definitely 'finning' either with tail or side fins. She is deliberately stirring up the sand. Other than that she is perfectly fine, eats like a pig and chases the Clarkii's when they get too close.
I guess as long as she's fat and happy I can live with her quirks!