What was your exact acclimation method? Sounds to me like this could be salinity shock, coupled with low oxygen and high ammonia exposure during acclimation.
test the salinity of the lfs water in the bag and drop an air stone in it to keep oxygen levels up. As soon as you open the bag, ammonia is beginnin to build rapidly so the goal is to get the out asap.
I usually get a steady drip of dt water going, about 2-4 drips a second, let the water double then dump most out, let that again more than double, then duMP most of that water out, and then let the water more than double again.
by this time, about 45 minutes should have gone by and the fish are now in mostly, if not all, of your water. Pull the fish out and drop them in the dt, of course if your are not QTing.
just my 2 cents.