A lot of fish do this. This is what is called "bedding". This is their safety zone.. If you look more closely and observe, you will notice that the Damsel that is doing this, will defend it's spot with uttermost aggression.. Mine would travel 3 ft across the tank to defend its bed if he thought the fish coming toward was threatening it's territory.
, In FW
Fishing, this is what you look for in the Lakes and Streams... Some would refere them to Crappie Beds, Bass Beds, etc...