Naso Changing colors

[primetime]

I have had a Naso for almost 3 weeks. He eats very very well. The other day, Iwoke up to find that one side of his face and half of a side were dark grey to black. I attributed it to maybe hitting a rock or something. Today the other side is discolored. He is still eating like a monster and swiming everywhere. Is this a normal coloration? He is still a juvenile I was told at the LFS. All water levels are normal with the exception of Nitrates being at 20 ppm. They were a lot higher before but I am doing water changes every few days and placed some "denitrate" in the sump in a bag/sock. Other fish include Yellow Tang, Purple Tang, cleaner Wrasse, Maroon clown, and 2 foxfaces. Tank size is 110G with LR and corals. Any advice would be appreciated.

Thank you

 

[Anonymous]

It is normal for fish to change colors, especially early in morning when waking up.

But yours may be changing because of stress-induced illness. 110G is way too small for a Naso along with a Yellow and Purple tang.

 

[primetime]

Even though the Yellow and especially the Purple are relatively small, 3", I suspected that the tank was not large enough for the 3 of them to coexist peacefully. The Naso now hides behind the rock continuosly and does not eat as well anymore. His face is now starting to change with nice bright yellow markings. Hopefully this is a good thing. Thanks for your comments JohnHenry I retested all my PH, nitrate etc levels and everything is looking good, except now my PH has dropped to7.8. I added Kent marine probuffer today. Will retest/change water tommorrow.

Primetime