One of my Lake Tanganyika communities pairs the shell-dwelling Lamprologus ocellatus ‘gold’ with the more open-water Paracyprichromis nigripinnis. The shellies are a lot of fun to watch because they are very territorial and do not realize that they are small. The tank is a 50-gallon ‘breeder’ with a matten-filter wall (Poret foam) that is air driven with two lift tubes. The substrate is mostly white silica sand mixed with a little bit of darker fine gravel for contrast. The gold ocellatus dig quite a bit, and I keep them busy by stirring up the sand every water change.