Which fish to transfer to QT?

[unsalted]

My PB tang has Ich and have been batlling for at least three weeks with Kick Ich, it was better for a while, but now it is REALLY BAD!! None of the other fish have shown any signs.
DO I need to put all of the fish in the QT that I will be lower the salinity in, or just the tang?

 

[unsalted]

I have read that tangs are more successeptible because of the smaller scales.
Is a 20 gallon tank big enough for my four fish?

 

[beth]

A testment to the unrealibility of the so called reef safe medications. Thank you for posting your neg exp.
Yes, treat all the fish. Depending on size of your fish, they may or may not be ok together in a 20. What are you using for testing salinity? Don't use a swing arm. You will never get an accurate enough reading which you must have for hyposalinity.

 

[timsedwards]

a refractometer is best, and i know isnt that expensive for you guys in the US. Over here they are $300, so I use a very high quality glass hydrometer and it works for me.
All the best,
Tim.