I have one, and he is very shy. He is very active, but if he senses me coming towards the tank, he scurries back into his hiding place. If I wait long enough, he will come back out, or if I am more careful walking towards the tank (i.e. quite, not walking heavy, etc.), I can sit and watch him without bothering him. He seems to be very sensitive to vibrations. The tank is on a hard wood floor that squeeks a bit, and I'm sure my footsteps reverberate throughout the tank.
He's my favorite fish, just very shy.