some ppl had very active elong, some had elong that would stay in hiding, really no way to know for sure. how the fish behave in the store can be very different than in your tank. like kevin said that often they will be skittish when first added to the tank but once they settle down they will come out of the shell, just matter of time.
they are ambush predators so if they hide a lot, it's normal, adding powerhead would help.