Clownfish acting strange

[schriss]

It hides most of the time near bottom at the cave and breaths quickly.
I ruled out water quality.
The fish does not seem to be harassed by any other.
I bought it 4-8 weeks ago and was fine until just few days ago, it would eat loads of pellets everyday.
It's not just sitting there, it sometimes swims out into open, would grab pellets only to bring them down to the cave and spit them out there.
It also often swims to Glass Anemone Shrimps living nearby and gets cleaning treatment. It actually does that every 30-60 mins and opens mouth fully for cleaning. Then swims back to the cave entrance.
There also is an anemone nearby, that's where the fish goes to sleep.
Here is a pic of it, was wondering if anything seen there is swollen?
Maybe it's constipation?
EDIT: It looks like it's actually blocking the cave entrance with its own body almost all the time.

 

[All6Fish]

In the pic he looks ****ed lol, maybe the water quality at the LFS is different than yours and he's adjusting? He does look dark, can you tell us what your parameters are? I know you said you ruled them out but someone may see something you do not.

 

[schriss]

I got him few weeks ago and I think it adjusted to water since then as was swimming around and eating plenty.
I don't think it's water as all SPS and LPS are open, usually when something wrong I see that on my Frogspawn and Acans.
But here you go (all RedSea test kits apart from Phosphate - Hanna):
PH: 4.2, Alk: 7dKh, PO3: 0.01, NO4: 0.50ppm, Salinity: 1.024, Mag: 1350, Ca: 450, Orp: 420
I think there could be few things: parasites, constipation or oxygen levels. Oxygen because I'm running ULNS and after replacing RowaPhos, I do see some die off on the remaining pieces of algae. But my Deltec skimmer provides aeration (it's sucking air from outside of the house) and on top of that I have one airstone in there just in case.
What else: NP BioPellets, Purigen, Carbon and mentioned RowaPhos.
Nothing changed in the tank lately.
I did dose some Vitamin C (Brightwell) yesterday and I might dose some today.

 

[schriss]

Or maybe it burned it's lips from accidental contact with Frogspawn or anemone?
Lower lip does appear a bit swollen and white, maybe that's why so often comes near Glass Anemones for cleaning...

 

[schriss]

Sadly, its dying now, I assume its parasites or some infection.
Two white stripes started changing color now and it became paralysed.

 

[schriss]

And it just passed away :-(
Mandarin and Damsel seem not affected at all and keep eating. No stress on any of the corals.

 

[fnicklaus]

Is the pH you listed a typo? 4.2? That would kill any fish...saltwater or otherwise. What is the real pH?

 

[fnicklaus]

Also, what is your ammonia level and nitrite? You better make sure everything is good before you add any new fish.

 

[schriss]

Yea, typo, PH is 8.35

 

[fnicklaus]

That pH is good. How about the nitrates and ammonia? I would watch your other fish closely for the next couple of weeks.