The Yellow Pyramid Butterfly, Hemitaurichthys  polylepis,  is commonly referred to as the Yellow Zoster Butterfly. With its vivid hue, the Yellow Pyramid Butterfly makes a stunning addition to any aquarium.  It has a dark brown-yellow area, the color of which may vary in intensity, fully masks the head and extends to a line from the first rays of the dorsal fin to the start of its pelvic fins. The rest of its body is white, peduncle and caudal fin included. Insertion of yellow-orange areas at the top of the side form a characteristic pyramidal pattern.  Unlike most Butterfly fish, the Pyramid Butterfly mainly eats plankton and is also considered safe for reef aquariums. The Yellow Pyramid Butterfly is quite shy initially and requires plenty of hiding places in the tank, so that it gets acclimatized easily. The Pyramid Butterflyfish is an extremely peaceful species, and should not be kept with overly aggressive fish, otherwise they will remain in hiding and may miss out on feedings. The Yellow Pyramid Butterfly can be kept singly or in true mated pairs, or even in small groups. The Yellow Pyramid Butterfly can grow to be 7 inches, and should be kept in a tank no less than 100 gallons if kept individually, and no less than 130 in kept in a pair. They can also be kept in small groups, in larger tanks. The tank should also have plenty of open space for swimming, along with plenty of  live rocks that can encourages the growth of natural algae.  It is very necessary to feed the Yellow Pyramid Butterfly at regular intervals, several times daily,  or it will occasionally pick at Xenia or other soft corals, but does not bother sessile inverts. They should be fed an omnivore diet, and should include frozen and freeze-dried foods containing algae that can even supplemented with dried Algae and vitamin enriched Brine and Mysis shrimp, finely chopped Crustacean or Mollusk meat, and frozen formulas. The Yellow Pyramid Butterfly is quite hardy and easy to care and makes a good fish for a beginner aquarist. The Yellow Pyramid Butterfly thrives well in a temperature range of 72-78??F  and pH of 8.1-8.4