Whats wrong w/ my percula? (video)

[MacDime]

Anyone know why my percula is acting so strange? He starts twitching like this in the sand or rocks sometimes then at times hes fine. He hangs out in the caves a lot too and isolates himself which is strange for him.

-For whats its worth. the other percula I added to the tank a week ago but they have not been fighting. They seems to take a liking to each other and go everywhere together.

Tank is 7 months old
Ammonia 0
Nitrite 0
Nirtate 0
Ph 8.4
Temp 80
Salt 1.026
Calc 440

http://i168.photobucket.com/albums/u173/rockerriot/th_DSCN4331_zpsdiczoefn.mp4 (http://i168.photobucket.com/albums/u173/rockerriot/DSCN4331_zpsdiczoefn.mp4)

http://i168.photobucket.com/albums/u173/rockerriot/th_DSCN4332_zps6zhshp1q.mp4 (http://i168.photobucket.com/albums/u173/rockerriot/DSCN4332_zps6zhshp1q.mp4)

[snorvich]

You mean A. ocellaris? Nothing I can see.

[Mark9]

He doesn't look right, maybe move him to a qt and try prazipro?

[Betta132]

He definitely doesn't look pleased. I'd guess some sort of gill parasite?

[MacDime]

Last time I tried qt my fish' died within a day of being in there.

[Betta132]

Was the tank cycled? My guess would be either the QT tank wasn't cycled or the underlying problem killed it. A QT tank is not lethal unless something is very wrong.

[MacDime]

It was cycled. I tested the water after death and ammonia, nitrites, and nitrates all ran 0. Ph was 8.4, salinity 1.026. I thought maybe my test kits were wrong and took a sample to the lfs store and they said the water looks perfect too.

My clown died last night and im really curious whats going on here.