Ghost shrimp tend to have poor survival rates when first introduced to tanks because of the incredibly poor handling they typically experience. Ghosts are more likely to be raised as feeders than anything else and seldom get treated as anything other than a very cheap, disposable commodity. It's why I buy my ghosts from chain stores rather than LFS's---the chain stores typically get smaller shipments and charge enough that folks aren't just buying 'em as feeders to the shrimp get slightly better handling. LFS's almost always have 'em as cheap feeders who aren't expected to survive more than a very short time.
Handled well, they're extremely hardy.