Dwarf Gourami laying on side?

[Nstr95]

I got 2 dwarf gouramis 3 days ago and one has been basically laying on its side the whole time, it’s sides look a little puffed out, it’s breathing heaving, and isn’t moving. He seemed to be gasping for air at the top a lot when I first got him and it really accelerated to this fast. I have an aerator and live plants in the tank.
Parameters are 0 ammonia, 20 nitrate, 0 nitrite, 300 GH (I know it’s hard but that’s my tap water), 0 chlorine, 120 KH, and 7.6 pH.
I’ve been keeping an eye on the nitrate and have done 50% water changes both tuesday and Wednesday once I saw they were high but it doesn’t seem to be helping. I figured it spiked because of the new stock.
The other Gourami is doing just fine

 

[Slaphppy7]

Very possible that it is Dwarf Gourami Disease, unfortunately very common, and hard to treat

Dwarf Gourami Disease: Everything You Need To Know Here

The the dwarf gourami disease only infects the dwarf gourami fish and has no known cure, but there are a few things you can do which I will go through today.

helpusfish.com

Iridovirus Dwarf Gourami Disease - Symptoms and Treatment - The Aquarium Adviser

Having a disease can be healed with proper medication and exercise. However, a condition with no remedy at all is alarming. If placed in a tank, the

theaquariumadviser.com

 

[Dajuyu]

Base on my experience out of 5 DG ... only 1 will be a survivor. Yes the DG disease are real of course and its just hit you even if its never your fault that its just lay helpless.

I rather stick with Gouramis only and yeah I lost 2 Powder Blue, 3 Red flame (just like yours) and 2 faded Orange DG over several years so yeah .. I am just staying away from DG for now.