My favorite, a clown loach. These love to be in a school, and the more the better. I would get 6 of these, and trust me they will get real cool and big. They live on the bottom. They will leave the ray alone. But, with this you would also need fish for the middle to top of your aquarium. For this I would recommend some sort of chichlid. But, you could also go more simple and add schooling fish. These could include, tetras, mollies, platies, or others.
