Isopods or?

[mid-island reef]

I'm thinking that if this was an acclimation issue, your fish would have died in the first 12 to 24 hours, and would not have eaten at all. I wonder if it's not an issue with oxygen levels in your tank. 65 Hex is a tall aquarium with little surface area. I have one and it's 30" deep. Do you have circulation at the bottom of the tank? or are you just useing your surface skimmer and the remora for flow.
One thing I have always believed in is, no matter how good you think the store your buying your fish from is, even if they quarantine their fish, you MUST invest in your own quarantine tank. All my new fish live in mine for a minimum of 2 weeks before they see the inside of a display tank.