Just a note -- IME they will not attack a fish they can't take on. They only seem to bother passive fish, like cories and otos. They don't got near my kuhlis and clowns at all and the thought of them trying to attack a juvie rainbow is humorous.
This girl went after my baby rainbow because it was small, stressed, afraid, and "stuck" behind a rock. It wasn't really stuck, but couldn't get out easily because it was panicking.
I doubt they would attack rams. Rams are peaceful but I bet they can kick up a storm when they want.
As for them defending their young, sure, but she wasn't defending. She was hunting.
Roan