Loss of color, twitching, not eating, not getting better discus

[Tiptoptank]

Water parms

20g QT tank with 3 discus,
heaters running at 90F
1 tbs of salt for every 10 gallons
PH 7.4
gh 7
kh 6 Iknow this is bad but the other discus are just fine and have been fine for a month
I have a sponge and a whisper 20 on the tank.
I feed san frans discus delight, tetra bits, mysisshrimp, beefheart, and bloodworms

Now out of the three discus one is doing poorly, It used to miss its food when trying to eat and now it doesn't eat at all. Its eye stripe is fade and it's eyes arn't the dark color like the other fish. It just seems to twitch and move slowly around the tank. When I syphon the tank the other fish go and hide but, this fish deosn't even see me there. It's top fin started to rot a week ago and hasn't rotted anymore. It keeps it's fins close to its body and is thin.

What is wronge with my discus?

I don't see any white poops either.

please tell me the meds and doses and amount of times and lenth of doses.

Thank you 8)

[Carol_Roberts]

Sounds like he has bad eyesight with is genetic. He should be culled.

Why is temp so high? KH, GH and pH are fine.

[Tiptoptank]

THis is not the fishes fault. He was fine 2 weeks ago. Today I found a big white spot on him. It looks like a piece of skin fell of him about the size of a dime 8(.

[Tiptoptank]

It died.

[Barb Newell]

Hi, sorry about your loss.

Do you have any plecos in the tank? Do you have 2 fish left now? I'd lower the temp on your tank and do daily w/c's.

Barb

[Tiptoptank]

I had them in a 20g bare bone tank. I did 25% everyday. I think this one was doomed to die. The only thing in with my discus were discus.