REPOST - Clownfish Spinning (HELP ASAP)

[Quiffles]

(I really apologize for reposting this, but I really need help ASAP.)
Hello,
I am looking for assistance in identifying this disease that had unfortunately taken one of my clownfish. The clownfish was perfectly fine for over a week after I had picked it up from my LFS. Today I look at my tank and notice that it was sitting at the bottom of the tank looking extremely lethargic. A few minutes after I notice this the clown starts spinning erratically and is very disoriented. It was having trouble swimming would get swept in the current and hit the glass. When I noticed this I immediately turned off my wavemaker, but it kept spinning in place in the water (I will post a video below of what the fish was doing, but warning it is hard to watch). Since I didn't know the cause of it I had put it in a separate QT container just in case it is an infectious disease/ parasite. Then less than an hour and a half later the clown had unfortunately passed away.
My water parameters are:
Salinity - 35.0 PPM
Alkalinity - 200 PPM
Nitrate - 30 PPM
Nitrite - >.5 PPM
Ammonia - 0 PPM
Temp - 78°

Any assistance would be helpful in figuring this out, I have another clownfish and royal gramma in the main tank and am now worried of them possibly contracting this disease. Again I apologize for the insensitivity of the videos below. It is heartbreaking to watch.

 

[praba775]

I will try to research it for you in google

 

[praba775]

So, uh, google say it is probably stressed out or it has a swim bladder problem. It could also be ammonia poisoning but I doubt that because your ammonia is 0

 

[praba775]

Sorry swim bladder disease.

 

[praba775]

Treatment of swim bladder disease in fish involves water maintenance, feeding changes, and possible antibiotics. Let the fish fast: If an enlarged stomach or intestine is thought to be the cause of a swim bladder disease, the first course of action is to not feed the fish for three days.

 

[praba775]

That article is straight from google