3 fish dead in 2 weeks and it does not look good for the rest

+1 fishoholic I would believe her just read post on MV it is moving... and I sympathies with her for what she went through.

It looks like velvet and the only thing to treat it with is Copper nothing else works freshwater baths while you QT all fish and then the DT has to remain dark and fallow for 3 months to be rid of it. I would QT each fish separately in 10g tanks then the least affected fish have a better chance of making it with out any stress from other fish the QT also has to remain dark. Ambient light from a room for feeding and remember to feed food that has been soaked with garlic and selcon to help with the fish's metabolism and immune system the copper will most likely affect their livers any tangs or angle fish their stomachs bacteria will be killed so they may not do so well.
I wish you all the best with this as you have to be dedicated to help these fish FW dips every day helps a bit. lower the salinity and raise the temp treat with copper. As posted while I was typing water changes. Thats all I can offer you the way of help, other than if they are not going to make it clove oil will put them down. I would dip them first and find out if they have flukes but that would be the worst case of flukes I have seen in a long time.
Bill