I wanted to chime in and ask, because I never saw anything mentioned, about what particular species of rams you're talking about. The German Blues and Golds stay really small, but I've seen Bolivian and Columbian Rams get quite a bit larger, like 3". Assuming you were talking about the Germans, they would probably be okay by themselves in a 3, but I wouldn't have any other fish with them in something that small because they can be rather fiesty when they start spawning.