Hardest fish to keep & what is your oldest fish

[Drock169]

Hardest fish: probably powder blue, moorish idol, mandarin dragonet and copperband butteryfly
All of these are alive and doing fine in my tank but I still consider them some of the most difficult to keep, along with the achilles tang, never tried to keep it though.
Easiest: My true perc, been alive for a couple years since i started the hobby