yellow tang
 

my tang has reddish splotchs and exhibits impaired motor skills.!20 g. tank,90 refuge ,all other residents appear healthy
any ideas please and thank you

Any pictures?
If I have to guess, it's a bacteria infection of internal organs of some sort. If it's my fish, I would get it out of DT put it in a QT and treat it with antibiotics. (don't dose antibiotics in your DT!). Then again, some people here think that netting a fish out stress the hell out of a fish. (I personally don't believe that). You can leave the fish there and hope for the best. Besides, antibiotics for marine fish are really a shot in the dark based on my experience because there are so many strains of bacteria and who knows if we have some kind of "super bug" that is resistant to antibiotics. But again I prefer to at least give the fish a chance. Bacteria infection is very serious for a fish.
Good luck!

+1 put in a qt immediately
Use a neomycin based antibiotic
Check your water conditions and do a water change if you have not done one recently

sorry no pics,thanks for the tips much appreciated.
I cut him off the red &green seaweed sheets and he looks better already....
I also finally put an outside air line for my (basement ) tank,Wow 48 hrs.and my tank is loving it,