Help! Fish breathing heavy, loss of appetite

[S0K]

Hello everyone,

So I am doing hyposalinity on my tank atm it's been about 2 weeks now because my kole tang had come down with a bad case of ich. He's still looking rather beat up right now but he is eating and I don't see any spots on him anymore.

BUT my yellow tang and my ocellaris clownfish have both stopped eating today and my yellow tang is pale indicating he is stressed and I see spots on him! How is this possible when the tank has been in HYPO mode?! I just checked the water params and they are as follows:

Sg: 1.009-1.010 (a bit high?)
Ammonia: 0
Nitrates: between 5 and 10 ppm
pH: 8 (I know it's a bit low...hard to maintain during hypo)

Tests done with Salifert test kits.

I am very worried because the yellow tang is always bright and bold and full of energy and the clownfish although generally kind of lazy always goes into beast mode at feeding time and he has proven to be the toughest fish I've ever had, he was my second fish bought since in the hobby.

Also, one of my chromis has gone missing since yesterday...he was tiny and I can't find him. No inverts or predators in the tank. I'm assuming he's dead but there's been no ammonia spike so can't be sure.

What's going on here? Is it because of ich?? What can I do I need suggestions fast I really don't want to lose these guys I feel like crying lol

I'm going to do a small water change right now

Oh the tank is 125 gallon fowlr, with 1 ocellaris clown, 1 kole tang, 1 yellow tang, 1 chromis and possibly 1 more chromis if he's still alive