My advice would is that you shouldn't by any ray. You said you don't want anything poisonous. Motoros are poisonous. You only want a pellet fed fish. You could probably train a ray to eat pellets but it certainly isn't their first choice. I don't understand why you would go through all the effort to get something you really don't want in the first place, get it eat only the foods you want it to, put your other fish at risk, and then get rid of it after a year or two.
I have 1 ray, so I'm not an expert but I do have experience and do my research, including listening to the people on this forum. My ray was a rescue. He went from a tiny tank to a tank that was better but still too small, and now to a tank double that size that will serve as his home until I get a monster-sized aquarium up and running for him. I have other fish in the tank with him but nothing that I will mourn if he kills them.
There are plenty of really cool fish you could get that would be much easier to take care of and more compatible with the fish you already own. Get one of them instead of a ray.
I have 1 ray, so I'm not an expert but I do have experience and do my research, including listening to the people on this forum. My ray was a rescue. He went from a tiny tank to a tank that was better but still too small, and now to a tank double that size that will serve as his home until I get a monster-sized aquarium up and running for him. I have other fish in the tank with him but nothing that I will mourn if he kills them.
There are plenty of really cool fish you could get that would be much easier to take care of and more compatible with the fish you already own. Get one of them instead of a ray.

