And they're expert hiders. I've had one in my 24g for 3 years now. It's a bit shy when there is sudden movement near the tank. Other than that it is out about cruising around the tank close to the rocks all day.
To this day though I still have no clue where it hides itself to sleep a night. I've search the tank at night with a flashlight looking for any sign of a mucus cocoon but have yet to see any hint of one. Must've really found a well-hidden little rock crevice somewhere to hole up in at night, 'cause very, very few crannies I can't see given that it's just a 24g tank.