They feel safer and happier with places to retreat from the attention or preceived threats. A couple of mine are happier with hidey holes or caves, the other 2 ignore the caves completely and just like to go up into the leaves of the plants. One will actually go to the back corner behind a plant, face away from the room and wiggle himself backwards into a space between the fronds. It has become his little 'cave' even though I can totally see him. I didn't think fish could wiggle backwards, but he sure did!