All-black longnose b'fly?

[f14peter]

Snapped this pic of these two about a month ago off the coast of Hawaii and as you can see, one of the longnose butterfly fish is all black ...

So what's the deal with this guy? I've never heard of an all-black longnose.

 

[dogstar]

Yes, rare, but not unknown...when placed in captivity, intrestingly, they turn to the normal colors. So dont get any ideas....