Hemitaurichthys polylepis a detritus eater
Hello WWM crew!
I haven't written in quite a while (although I am a daily visitor to your website) and I would greatly appreciate your insight on the eating habits of the Pyramid B/F compared to my observations.
First the story: I saw some of these at a new LFS in my area and my first thought that was that they were probably a doomed aquarium species. I liked them though and was curious enough to visit your website and see what you had to say about them. Based on the articles I read like http://www.wetwebmedia.com/Hemitaurichthys.htm  I was happy to learn that they actually seemed to be a pretty good aquarium candidate. 
I returned to the LFS and bought the last one they had. Everything is going great with the specimen (had it for about 2 weeks), but I am surprised to observe that he actively eats the feces of other fish! I also have an area in my tank that tends to collect detritus, and this area is now completely clean. I haven't added anything other than this b/f, and although I haven't actually caught him eating detritus off the bottom of the tank, I have to suspect that it's him doing it. 
Currently this tank gets fed a combination of frozen blood worms, live black worms, spectrum and Nori 3 times a day. The pyramid b/f eats it all except the Nori, which is to be expected (haven't personally seem too many b/f eat it, but I have tangs in there). 
My question is: have you ever heard of pyramid b/f's eating detritus? I am just curious because if he continues this behavior it would actually be a nice bonus for being a steward to such a beautiful fish! 
Thanks for all you do and have a great holiday weekend. 
<To my knowledge, these butterflies are zooplankton eaters on the reefs. He may be stirring up the detritus/feces looking for worms to eat. James (Salty Dog)>