There is always a couple in every crowd with rogue behavior. Nature always seems to work best that way; it is sometimes referred to as variability.
Bruce, I currently have two cages of yellow perch that are similar sized as your newly stocked perch. My caged perch are confined to the upper warm water layer and my near surface water is running at or slightly above your water temperatures (80F-82F). I will experience your current hot weather for the next several days. Stay in contact with me through August as to how the perch are feeding to compare notes on temperature stress levels of your perch.
