Tell me about convicts and firemouths. Does the substrate really matter? I find that one prefers a sandy bottom while the other prefers a rocky bottom. Can I go with gravel and have all be happy? How's this for a setup? 1 convict, 1 firemouth, and 1 green terror in a 55G? I am doing research, but haven't found a good place that puts all of the information I am looking for out there. Your help is appreciated.