thanks all, my dads boss has informed me he wants lava rock, black sand, and black background, to contrast the fish. this made me think of two things, a jack dempsey green terror and flamemouth, or a pair of oscars being one albino and one black, how big should this tank be? is it even possible for me to tell the diffrence in sex? lastly, i have heard a bit about lava rock messing with ph or something similar a while back. Thanks for the help everybody! (the single fish like that seems very smart, espesially with the reasoning provided by cacichlids).