Spending all that dough and not using a QT setup. What's your salinity at? Most LFS run their stuff real low at ~1.017(for reasons I have yet to understand, because it's widely accepted that crypto will happily live at that level), it's not suggested to raise salt level by more than .003 per day, even less, to be safe. Salinity changes cause all kinds of fun stuff, like ruptured cells that can kill a fish "for no reason" down the road! It's always wise to know before buying a fish, what their current conditions are, so you can match it in a QT setup. I know a 20min bag float and swapping a few cups of water is advised, but it's garbage. Call ahead and match the params first and get the fish out of the bag ASAP, as to not subject it to ammonia poisoning. Fish can tolerate a temp change. If you've ever been in the ocean on a reef, deep currents are constantly mixing cold/warm water together. The fish you have that died, died for a reason. Just because you don't understand why, doesn't make it inexplicable. Maybe it was the collection method, or something else all together... Whatever the exact reason, I'm gonna go out on a limb and chalk it up to inexperience. There will be a lot of people who will say "i float bags, been working fine forever".. My grandfather smoked for 70yrs and didn't die from lung cancer.