I've kept a fair number of butterflies over the years. I would put Pakistanis in the "average" category for butterflies longevity. In comparison, I feel they are on the lines of Pearlscale or Raccoon but not as easy as an Auriga but, much easier than a Copperband. The important thing is that, like most butterflies, they need a large tank or they get stressed and die. They are also much more reef safe than Longnose or Copperbands. Many people will say they pick on polyps but they prefer SPS, although they do require several daily feedings to avoid potential nipping at sessile inverts.