Most Cichlids are very 'itchy' in the sense that they will never leave anything alone as long as it can move or be moved. If you are planning to keep the mBuna, the rock dwellers of the Lake Malawi, or the Convict Cichlid of the Central America, you don't want to risk planting the tank. The reasons you should not introduce any plant into the tank if you are keeping any fish as mentioned above or fish with that behavior are, firstly the fish will nip the plants from the tips to the roots. Eventually you will be left with stalks floating around. Secondly, one of the favourite interests of these fish is to move the gravels and pile them up to make a small hill. In the end some portions of your tank will be filled with hills while other portions will be left totally cleared. If you do have any plant in there, it must be again floating around. To prevent too much gravel transfer one method has been suggested by the experts. The use of the egg crate has been very effective. To apply it into your tank, first you fill up the tank with a layer of gravels, then put a piece of the the egg crate above that layer of gravels, and above that egg crate you introduce another layer of the gravels. Now, your 'itchy' fish can move only the gravels above the egg crate to their hearts' content but leaving the one bellow the crate untouched. I hope this help solve the problem if you are facing it.