Yeah, I think I remember him saying recently that his blue spot jawfish died.
That doesn't bode well for me that his died and his tank is perfect!! Lol
there's many factors to consider
fish may have been sick before he got it
major stress from shipping in mail (major temp changes or even just being tossed like a rag doll)
fish are very fragile and need to be handled that way
fish may not have been fed at warehouse for days causing starvation sometimes they appear to be fine when you get them and wham its too late ,it may eat after you get it but the damage was already done.
no fish is bullet proof even I lost a few
even if you acclimate there s still a chance there is a water parameter difference salinity,temp,ph,nitrate,nitrite ect
there's many more factors than I mentioned but I think you get the idea
don't get discouraged about a fish because someone lost one it happens
even the most experienced fish keepers loose a fish now and then
it's not rocket science and things just happen
hope you understand what I'm trying to say