Yellow tang turning red

[Mrs. Fox]

Just yesterday I noticed my tang has started to go red near his rear end, and he has what looks like a small puncture mark above his right eye. He's in a 90g tank with 2 clowns, a longspine urchin, a few shrimp, an emerald crab, 2 small damsels and a red knob sea star. Could he have been pricked by the urchin possibly? He is still eating like a champ and swimming fine, Isn't showing any signs of illness other than his discoloration. I read it may be a bacterial infection, but due to the small mark above his eye I thought he may have been poked by the urchin. The redness isn't raised from the body, it appears to be redness under the surface rather than an irritated exterior.
PH - 8.1
Salinity - 1.022
Nitrate/Nitrite - 0
Phosphate - 0

 

[Martin H. Lawton]

got a picture?

 

[Mrs. Fox]

got a picture?

Sorry It's kind of blurry, hes skittish

 

[Humblefish]

Did you recently move him from one tank to another? Or did salinity suddenly fluctuate? YTs are apt at showing signs of "Acclimation Stress" due to their light colored skin. Scroll down here until you see Acclimation Stress and a pic of a YT beneath it: http://chucksaddiction.thefishestate.net/disease.html

This may not be the problem at all, but let's rule it out first as a possibility.

 

[Mrs. Fox]

Did you recently move him from one tank to another? Or did salinity suddenly fluctuate? YTs are apt at showing signs of "Acclimation Stress" due to their light colored skin. Scroll down here until you see Acclimation Stress and a pic of a YT beneath it: http://chucksaddiction.thefishestate.net/disease.html

This may not be the problem at all, but let's rule it out first as a possibility.

He has been in this tank for 4 or 5 months now, but I just did a water change a few days ago. I will check to make sure my refractometer os working properly and test tank salinity again. The redness shown in that picture is very similar to what he has, so I will double check.

Thank you!

 

[Mrs. Fox]

His red has started to fade, specific gravity had changed by .001.. But he appears to be doing better now. Thank you!!