Tank lighting can and does affect cichlid behavior. I have posted before about how some fish become killers at night whereas sometimes everything is calm and peaceful. See Lights on or lights off?, Lights off equals calm, When the lights are off, it’s not always tranquil. My show tanks are all individually lighted. My larger tanks, which are community tanks, also contain considerable cover (e.g., caves, rock work). The lights on those tanks are only on for a couple of hours each day. However, those same tanks are also exposed to ambient lighting (e.g., window light or room lights) about 14 hours a day, leaving my fish in complete darkness for the remainder.