I recently started a quarantine tank (28 gallon) for a False Clown, Royal Gramma, 3 Blue Reef Chromis, Firefish and a Scooter Blenny because the main tank (65 gallon) was breaking out with Ich. So, I individually dipped them in freshwater and methylene blue for 5 minutes (proper pH & temp. with bubbling) and placed them in the QT tank. A day later, I lost the Gramma and Chromis (they seemed to be the most infected, so I thought they were going to go anyway), but the Firefish and Scooter Blenny are doing fine. I thought the Firefish wouldn't be able to handle the treatment because of what I've read about it being sensitive. The Clown is doing okay, but it might be a while before it regains full health and vigor.
I didn't know whether or not to treat the Scooter Blenny because they seem to be immune to Ich. I guess it has something to do with their toxic skin properties. I was wondering if it might give off toxins during the dip, so I made sure to dip all fish individually and discard the treatment water. I decided to I dip the Scooter Blenny because he could potentially be a carrier of Ich.
I'm not very experienced in this field, but I did read a lot of material at
WetWebMedia-Marine Aquarium Articles and FAQ's and got a lot of good advice on QT. The freshwater dip is supposed to kill off Ich due to low osmolarity, but the methylene blue is only there as an oxygenator and disinfectant. I'm planning on letting my main reef tank go fallow (without fish) for several months to let the parasite die off before I re-introduce any fish. I will still monitor the QT tank for Ich. If it shows up, I'm planning on trying the hyposalinity treatment before trying formalin or copper treatments.
I should have started out with a QT tank before this mess happened!
Good luck!