The skin condition looks to be in the ribs of the tang (skinny because its not eating)
Don't change too much water do up to half at a time you don't want to stress them out more than you have to
Are usually don't quarantine leopard wrasses because they usually don't do well and they sleep in substrate but you seem to have it eating
I can't seem to see the red marks is it possible that these red marks are coming from banging in to the glass
Yea. The wrasse is eating. Mostly smaller stuff but very actively chasing food in the water column. The red mark that in talking about is on the tip of his head. I actually can't make out if it's a rash or just his actual pigment changing. But he's a black leopard, and I'm not sure if they're suppose to contain red. He was eating through furan and CP.
As for the tang, not sure of what do to. Maybe he's stressed because of lack of hiding places. I have pvc elbows on the tank but he doesn't enter them. He hides under a heater.