Brook, Velvet, Something else?

[venomcc]

So this really puzzles me, this tank has been disease free since inception. It is part of a much larger 400 gallon system that has gone through strict qt procedures (prazi + copper). No new fish has been introduced into this system for at least 1 year. No coral for at least 3 months.

So I've no answer to this happening on my frag tank. Other than this clownfish, there's a six line in the same tank which appears unaffected. I have dozens of fish on this system so this is like total worst case scenario, i do not have the scale of a hospital system to house all the fish, really at a loss for what to do.

 

[vetteguy53081]

My guess would be brook . You may give this fish a FW dip for temporary relief.
Similar symptomatically to Ich, this is also a parasite that primarily attacks the gills first. At the onset, fish may scrape up against objects, rapid respiration develops, and fish often gasp for air at the surface as the gills become clogged with mucus.Very quickly the fish will become lethargic, refuse to eat, and its colors will fade. The most noticeable difference that sets Brooklynella apart from Oodinium is the heavy amount of slime that is produced by a fish that has contracted this parasite. As the disease progresses, a thick whitish mucus covers the body. This will usually start at the head and spread outward across the entire body. Skin lesions appear and it is not uncommon for signs of secondary bacterial infections to arise, such as redness and fin rot.
Quick cure is my choice of treatment as it contains formalin. So does ruby rally pro. Typically a standard formalin solution is mixed with either fresh or saltwater in a separate treatment container. Initially, all fish are given a quick dip in the formalin at a higher concentration, followed by continued treatment in a prolonged bath of formalin at a lower concentration in a quarantine tank (QT). Of course, the longer the fish are exposed to the formalin treatment, the more effective it will be at eliminating this disease.