Just one more note that might help you out a bit. You might try this sight;
http://www.wetwebmedia.com/monofaqs.htm
This is a couple of quote's from this sight;
"Do review circulation, oxygenation, and water temperature. Monos are classic "surf zone" fish and they are hyper-sensitive to stagnant, oxygen-poor water. Given enough oxygen, they're tough as old boots, but if the water lacks sufficient circulation, they turn grey, gasp, and sicken very quickly"
"Monodactylus can be converted to marine conditions quickly. I'd use the drip method across an hour, as if they were swimming through an estuary, but yes, you could in theory dump them straight in."
Monos also require a ph of 7.5 to 8.5
Hopefully you are using reef salt or equivalent, and not aquarium salt as there is a difference.
I would definately rule out ich if your salinity has been high enough brackish as ich does not fair well in brackish water.
I wish you luck and hope you can get your tank turned around soon
