Velvet disease

Question
Hi there! I have a 24G Nano Cube, i have about 8 kilo of liverock and some soft corals.  I recently lost some of my fish to the dreaded Velvet disease! At the time i didnt know it was velvet, i thought it was down to stress as the salinity was pretty low, 1.021. So i gradually raised the salt level, this didnt work and my 3 clownfish and coral beauty all died. My Blenny, starfish and two shrimps they all survived. The disease happened a month and half ago, i added Oodinex to try and help the rest that were in and like i said they have survived. Since then i have done partial water changes every week and also got myself a poly filter to purify the water. Had my water tested at the fish store everything was fine so i bought two green chromis they died a day after adding them from the Quarantine tank. Im just wondering when would be the best time to add another fish as i dont want to buy anymore that will just die when they go into the display tank. And why has the Blenny starfish etc survived i dont understand!

Many Thanks Paul

Answer
Hi Paul. Velvet is a parasite that can not be completely removed out of your system except by a copper based medication or by having the tank free of a host for a period of 30 days. It also only infects fish(not invertebrates) and your blenny must have a really good immune system to not be infected enough to do him in(although he is still being used as host for this parasite he is just strong enough to not die from it). My suggestion to you would be to put the blenny in your quarantine tank and run your main tank fish free for thirty to forty days. At that point the Oodinium will have been unable to complete its life cycle without the presence of a host and will die off. Any other way (besides using copper) will leave your tank with velvet still present and will in the future break out on your fish if anything stresses them out. Remember no fish host for thirty days and your tank will be velvet free guaranteed!