clean water, good food and a good ratio of females to males. But even in less then optimal conditions mbuna can breed, all you need it a male and female.
Make sure you have at least one male and one female! :joke:
I've always noticec a tendency in these fish to breed, esp. after a water change where the new water is 4-5 degrees cooler than the tank. Never fails to put them in the mood for love!
I have never tried adding chemicals to help with spawning. But most africans(mbuna especially) dont' need anyhtign to help them breed. If there is a male and female you will have babies. Most people can't find enough room for all the babies.