Here you are wrong sir. I have orinocoensis and large catfish with my rays and no trouble at all. Only downside is on my feeding account. I currently have 3 diffrent catfishspecies in my tank with 4 rays 2 orinos and an large cigarrshark. No problems at all. So peacocks being aggressive on the rays is wrong IME. Same goes with the catfish.True true. I noticed most ppl don't get enough substrate for a ray if any substrate at all. Granted more often then not the ray is the only bottom dweller in the tank in most tanks.
And rays staying buried 24/7 is totally wrong. As Matteus said an ray that stays burried is stressed. Thats their way of hiding from something. An healthy ray should always roam about and explore its surrounding. And when it comes down to substrate it an personal preference. I have grow out tanks with rays with substrate and almost no substrate in my large tank.