The cichlid rocks are basically caves. Except for some of my Tanganyikans that use the caves to protect their eggs, I agree many cichlids especially mouth brooders have little use for caves. The thing about the vinyl fence posts is that they are open both ends and big. They are more of tunnel system or maze and pretty uncavelike. (If that's a word.) If I see my Chalinochromis adults in a cave, I can be pretty sure there are eggs or fry in there. Otherwise they are outside of the caves.