How long have you had your maroon? With a tank your size...depending on the behavior of your current maroon (what is his territory like in your tank), you may or may not want to do it. If he is bold, shy away. If he is pretty docile and agreeable with tankmates, you might be able to get away with adding one smaller than what you currently have.
I started out with 2 and ended up with one...they evidently weren't buddies!