what's wrong with my yellow tang???

[coolbreezebc]

I have a very healthy yellow tang but tonight I noticed that it had red streaks along the base of its body by the fin and red streaks in its top fin. There is also a small reddish spot near its spike fin. It is acting perfectly normal.

[Kryten]

A long time ago I had a tang that displayed similar symptoms. I know at that time I had very high nitrates. Not positive that's what caused it, but after I got that under control he got better.