they tend to have that reaction to each other.
when i introduce ghost shrimps to a tank that they may get eaten in i alway always alway :
aerate the bag for gas exchange
leave them in the store bag for first day no food
second day drop in some peas *ghosties love peas*
third day morning peas then after 6-8 hours from drop i scoop out the ghosts and drop them in the tank.
i do this cuz i have noticed most ghost shrimp come is poor enough health that they die in 24 hours or live just fine. i feed peas cuz it is a healthy choice food for all but my bettas and even bettas can handle the ruf***e that is half digested in the shrimps gut. then if they are eaten i all i am out is a 20 cent snack for my other pets :) and i know not to use them again for that tank.