Controlling Aggression Through Feeding-
Before we start examining the Cichlids themselves, we are going to take a quick look at aggression, the most common problem facing Cichlid keepers. Aggression in Cichlids is caused by a number of things. In nature, Cichlids live in relative density, and are under constant pressures to find food. They establish territories to help ensure their survival in these crowded conditions. The first thing which drives aggressiveness is food. By establishing a sizable territory in nature, each Cichlid creates its own little "backyard garden" to harvest, ensuring a good supply of food. Fish which consume the same foods are obviously competitors, and are driven away. Secondly, fish need territory to breed. Females are only allowed into a males territory if she is willing to breed, if not, she is chased off. Males of the same species are also driven off, because they are competition for the females of the species. There are a few things you can do to "control and manipulate" Cichlid's aggressive tendencies in order to reduce the risk of "murder".
First, and most basic, aggression can be reduced by keeping your fish well fed. The basic aggressive instinct is to ensure that each Cichlid has enough food. If a fish is hungry, it will be more aggressive. Therefore, we usually recommend that you feed your Cichlids 2-3 times per day (about as much as they can consume in a minute or two, leaving nothing left), although occasionally it is good to give your fish a "day-off" by fasting them for a day. Be extremely careful when feeding this frequently, as new hobbyists which are told to feed community fish "only once a day as much as the fish can eat in one minute" often still overfeed their fish. Despite the fact that hungry Cichlids are more aggressive Cichlids, it is better to err on the side of caution and feed them less rather than more. The one definite sign that you are overfeeding you Cichlids is that they appear full, and do not have much gusto when feeding. A healthy and properly fed Cichlid will always appear VERY hungry.