My OB Peacock cichlid likes digging, moving and rearranging the substrate around the tank. Is this typical of cichlids? I usually put out a fairly level base of substrate and within a few days to a week, he clears out the substrate from the front of his cave, almost to bare bottom, and usually moves it to the back of the tank, although some to the side also. I've attached a couple photos of the tank. Does he not like the substrate or is this just something that cichlids do? We tried a sand substrate, but my husband didn't like it at all. Currently it is a combination of sand and gravel.