Any ray is going to be at the bottom a lot of the time, they are bottom dwellers.
But, as they get used to you and their tank, rays will swim up the sides of the glass and some will swim against the current of spray bars, filter outlets, and even bubblers.
Even though my ray cruises the bottom of the tank most of the time he is not boring. He is constantly blowing in the sand, exploring decor, and looking for food morsels. He has learned to come to the top of the tank and "slap" when I come in the room to feed the fish. He is a very cool fish to just sit and watch.