Yellow tang with red spot/hue

[xeanliao]

Not sure if it has anything to do with too much water flow, my yellow tang has been a lot less active ever since I added a maxspect gyre to my 90gl thre week ago.

Today, a dark red spot appears on on side, some red hue appears on the other side near gill. Not really eating :-(

Should I take some immediate action? I for sure can lower down the water flow immediately. Or should I move it to a QT?

See attached picture, any question or advise are highly apprecited.

 

[lmforbis]

Kind of looks like an injury. The fish is kind of thin. Make sure it is getting plenty of high quality herbivores food including sheets of dried seaweed.