Help identifying disease with Skunk Clown

[misadventure]

A few days ago, I posted a thread questioning how to treat Uronoma in some Chromises I had. Well they all got red splotches and died in quick succession so I'm still suspecting that was indeed the culprit.

Anyway, I started treatment with Paraguard 5 days ago because I noticed my Pink Skunk Clown's gills looked inflamed and I thought it might be related to the Uronema too. Also, right after treatment began, my Banggai Cardinal developed a filmy area on the rear portion of his body and died. He was new to the tank and as far as I know, had never eaten since he arrived.

I'm now left with the Pink Skunk Clown, Tomato Clown, and Neon Dottyback. The Tomato Clown has seemed generally healthy, though I saw a potential ick spot on him a couple days ago but now it seems gone so I'm not sure if it ever was one for sure. The Dottyback's fins are frayed a little, but they've been that way for a while. He's got a little pale spot around his "nose" that I'm not sure is normal or not, but that's been there a while too. I'm most concerned, and I admit most attached, to the Pink Skunk Clown because I've had her for many years and her gills have looked inflamed for the last week or so. I was thinking initially it was related to the Uronoma, but she's been acting pretty normally and eating, and not seeming to get much worse the last few days, unlike the quick demises of the Chromises and Cardinal.

I have attached pictures of my Skunk Clown and Dottyback to show what I'm talking about. Am I doing the right thing with the Paraguard, and if so for how long should I treat? Will this treatment harm my live rock? I have Prazipro on hand too now. I'd appreciate any input and thank you!!

 

[Newsmyrna80]

Were any new fish introduced to the tank recently?

 

[misadventure]

Yes, there were a few fish introduced recently. They were the two new Chromises that died, the Banggai Cardinal which also died, and a Tomato Clown, which so far has seemed healthy. Needless to say, I've learned my lesson about the value of a quarantine tank and won't be introducing anymore until this tank is under control and I have my quarantine tank set up. FYI this is a 55 gallon tank, almost a FOWLR, but I do have a cleaner shrimp. I know Paraguard isn't recommended with inverts, but I felt like it was worth the risk to save the rest of them hopefully. I don't plan on any more inverts for the future.

I tested my water a few days ago and my ph was around 8, nitrite 0, nitrates around 20ppm, dkh was high though around 13 or 14. My calcium was also super high, something like 900 (about twice the recommended amount as I understand?). I'm starting to realize how messed up my well water probably is and I don't have an RO/DI. I'd like to just make a nicer FOWLR out of this eventually though.

Sorry the clown pic isn't very good, but it was about the best I could get that shows some of the gill redness. It kinda looks like the scales are protruding just a little over the gills too.