oh and keep up with daily water changes (at least 15%) if you actually plan on letting them grow up. if either of the parents get to aggressive with one another (it has already happened to me...twice) seperate them if you can either with a divider or just taking one of them out of the tank. i don't think you'll have this problem in a 55g but it's something to be aware of
Make sure they have a cave (or 2-3) to feel comfortable in and lay eggs.
I would advise not to do daily WCs as frequent may stress/disturb them. I do a weekly 50% WC, and IME a large water change can induce spawning. But I have heard of people having success both ways.
Keep an eye on the female, her colors may get more intense as she becomes gravid. Do they exhibit any pairing behavior? Do they swim in sync or brush up against each other, flare gills, lip-lock?
As long as the nitrates are below 20 ppm and the pH is between 7-8 you should get positive results.