Will a tomato clown get along with a maroon one?

[Aquattro]

No, they won't. The maroon is likely going to get too big for a 20. They're big clowns. Tomatoes are also aggressive (most clowns are).
Maybe get rid of the maroon, keep tomatoes instead. Yes, either a mated pair, or buy them really tiny so they grow into a pair.

[my2rotties]

No they will not... I had to remove my tomato from my tank because the maroon would actually hunt him down to beat him. I have a seven foot wide tank and the tomato lived on the far side from the maroon, in his own nem. Maroons get grump at people when they dare to stick their hands into the tank as well. As pretty as they are, they sure are not friendly.