If it is flat worm you can try and get as much of the white stuff out of the tank. Do a 20% water change to alleviate the water conditions. If it does not improve the out break at least it will give you more time to figure it out. Best thing you can do is move your fish to another tank all together. If the nem dying then there is little you can do to help it out, but you can help save your fish. Does the water smell? Nems smell really bad when they die really bad.

Take a sample of the white stuff to Red Coral they may know of a couple of tests that they can do 1 would be to put some on a slide and under a microscope. One can get a good idea for a slide as to what it is if you have contacts in a lab. They can match it up to pics of slides they have on file or one could try and contact a university and ask some there if they would like try and figure it out as a lab assignment. Marine bio Lab.

salinity should be between 1.023 -1.025
Temp should be no lower than 75 but should be at 78 or 79.
I keep mine at 78 but has droped the 76 for a few days when it gets realy cold in my basement, It all depends on the Nem that you have.
here is and artical on Nems.
http://www.saltcorner.com/sections/z...s/anemones.htm
Bill