Shell Dwelling Cichlids (Neolamprologus multifasciatus) are a good choice if your aquarium is small,since it is one of the smallest cichlid species and is also very docile and non-aggressive.however they will not fare well with Discus because of temperature.Shell Dwelling Cichlids thrive in temperature of 78 - 80° F where as Discus need temperature above 82° F.