blonde nasso It got dark

[dkz]

I have had my blonde naso for 3 months, but it has turned dark, it is about 3-4 cm

very balanced diet with pellets, nori and frozen

 

[KrisReef]

Almost looks like a powder brown tang?

I think it’s trying to get along with the Purple and it could be suffering from aggression?

 

[exnisstech]

Need a better shot under some white light. I'm with @KrisReef to me it doesn't look like a naso but it hard to tell from the image. I see nothing indicating it's a blond naso, but it could be the lighting.
EDIT : naso along with many other fish can drastically change color when stressed and many change color at night.