Some information about the Pyramid Butterfly from my views and some from the internet.
Scientific name: (Hemitaurichthys polylepis)
Minimum tank size: 55-100 gallons is the range I am seeing online, I would say 100 gallons because this fish swims alot.
Food: Mine love Pellets, I have a mix of different Pellets and the two I have eats them all. I feed a mix of Frozen food later in the day and they seem to like Mysis Shrimp now but did not in the beginning.
Care/Compatibility: So far seems hardy and gets alone with Tangs, Angels, Chromis, Anthias, and more. The do well in pairs, the two I have get alone along fine. Online it is said to be a community fish and one of the best Butterflyfish to have. They say they can be kept single, in pairs and in groups. (something I may find out about if I add another one)
Reef Safe: So far I have not had any issues. I have mainly SPS corals, I do have a tube anemone and the Butterfly has not bothered it at all. Online they say they are plankton eaters and if feed well they should not bother your coral.