All the fish in my main DT that were not QT had different salinities.LA usually ships in the 1.017-1.018 range, is that where you had your salinity?
I doubt the copper at 1.0ppm has anything to do with it. I just acclimated (float and release with matching salinity) 4 Wrasse last week directly into 1.75ppm and they are doing just fine.
However, they were very close to bag salinity. What's the downfall to not matching salinity ?