He's in a large, mostly bare tank. He probably feels vulnerable. Adding more fish would probably be a good idea. A lot of SA cichlids are shy as single fish when they've been introduced to a new environment, especially if he was packed into a tank with a bunch of siblings before you bought him. He may feel more comfortable if he sees other larger fish eating and acting normally. I've taken shy fish from smaller tanks and mixed them into large community tanks, and their attitudes change almost immediately.
