the Hillstreams seem to prefer a flatter surface, but the sticks I have along the ends were really like Hillstream hideouts, they used to be there all the time, but after I added some 3 inch rocks along the bottoms of the Bamboo, they really like the rocks the best... although after adding the pagodas, they are all over those, & I imagine, once they are covered in biofilm, they'll hang out on those most of the times...