Can you help with with my cichlid dilemma?

The group of Malawi cichlids known as mbunas are actually pretty "peaceful" among their own kind. The males may exhibit some aggression, though with enough hideouts they should be fine. Malawi cichlids are the most colorful, but they are quite belligerent as you know. Zebra cichids are also good, but their tankmates should be chosen wisely. A slightly cooler temperature can help curb aggression. As a previous answerer said, crushed coral and aragonite are popular substrates as they buffer the pH to the cichlid's likings.