i dunno if id ever put an oscar with a ray, hes pick it to death me thinks.
I myself have a juvie retic in a 75 for the time being. He was sold as a teacup ray, i will upgrade as he grows and i feel he needs it. Ive herd of members breeding them in a 90 gal which is only a 75 taller. So for the time being and depending on your ray. your 120 ray work for a long time.