I My LTA Dying HELP!

[ChloeApple]

Hey, just wondered if my LTA nem is 'dying', as it's my first one and not sure of their behaviours yet.

Parameters are fine(checked all today. Inc. water changes). I have great lighting as well. I've attached pictures to more clearly demonstrate.
Basically all was fine (had it around 3 weeks), tank is pretty new (too new for a nem, i am to be told) around 3 1/2 months now.
So All was fine with the nem, then within, an hour or two all it's tentacles shrivelled to 1 tenth of their normal size in width and length. I have seen no excretions. Then i fed the fish as normal, the tentacles appeared to go back to normal for a couple of minutes. Then afterwards more and more tentacles began to shrivel.
Then the nem decided to completely close up with a few stringy looking tentacles still out. It appears to be out slightly now (not nearly at it's full size) there is no gaping mouth or white/brown excretion. I think it maybe just having a poo. It is fed half a muscle every week or maybe 2. It also appears to feed off the frozen fish food given to the others (defrosted first).

One more Q. How much to feed fish everyday? I have 4 chromis, maroon clown and pj cardinal and blue fin damsel. three shrimp. thats all. Also corals seem to be thriving has no deaths as of yet.

Any help really appreciated

 

[davocean]

Well of course a new tank can be part of the problem, but first thing I see is it is on rock, and LTA's are sand dwellars.
It should be down in sand bed, which makes me wonder why it has not gone down to it yet.
What lights?
params w/ numbers really should be given.
Normally when I see those blue green purple mix of LTA they either do not do well, or they adapt to what their natural color really should be, beige and an accent color, usually one color on those accents, purple, red, or green most common.
It does not look terrible.
Spot feeding is something I hold off on until a new nem settles, the mysis or whatever you feed fish is fine if it picks up any.