I have been keeping emeralds for a couple years and have noticed that some just dont make it. I have some that are a few months old at most, the rest seem to die off rather quickly. I have good water parameters too, I have just chalked it up to them not being super hardy critters.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.