Depends on how long it was in transit, how long it was in his tank, what's taken up residence in it that may have died... If it is only going to be out of water (or transported wet) for a very short time then you should expect little die off, but if it is going to be in transit for any longer than 24 you may see a small spike (what proportion of your total rock is it? 10%? Your current rock can handle the bio load; 90%? May overwhelm your tank if it has sufficient die off).
I had LR
.com rock shipped to me over night and put it straight into my tank. I saw no spike from it at all. It was about 30% of my total rock volume at the time and it was full of its own life to carry through the minimal die off.
I would probably put it straight into my tank but be prepared to do several 20% water changes to get things back in line if need be. Good luck!
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