My Blue Tang which I have had for almost 2 years suddenly lost it color. Eventhough I can still see where his blue and black color was, his pigmentation is extremely light. It is almost like he is powder blue. I checked all my water parameters and they are all within their normal limits. I haven't changed anything in the tank recently. The only recent change has been my feeding live phytoplakton that I purchased from a local reefer. But, I haven't used the phytoplankton in a couple of days.

Any ideas what or where I should look?

thanks,

Jerome

Has the coloration appeared to return to normal since you have stopped feeding the Phytoplankton? If their is a noticable difference I would continue to restrict from feeding him Phytoplankton. I really don't know what else could be wrong. Maybe someone else can chime in.

it IS normal for the Hippo Tangs to suddenly lose thier coloring. i have noticed it MANY times in mine AND at the LFS that i work for (part time). it is more common when they sleep, but does happen from time to time when they are not asleep.

you may want to keep an eye out for some type of stress factor in the system, and keep his diet varied. this could be due to lack of algea or meaty foods also. or another fish "picking" on him.

HTH

first off remember the fish is not eating the phyto, and this likely has little to do with it.. many stresses can cause the color fading to occur.
As Bobby mentioned its is common for them to loose there color while sleeping and "occasionally" during the day, but if it is like this all day, or multiple days something is wrong.

are you feeding it Nori, or other veggie? this is a huge requirement for all tangs, they need lots of veggie in there diet (phyto doesn't really count because they don't eat that)