BLACK CALVUS Altolamprologus Calvus "Congo"

Although territorial, it’s generally peaceful towards fish it can’t fit into its mouth, and is a good addition to a Tanganyikan community. However it tends to be quite shy, so aggressive or very vigorous tankmates such as Mbuna should be avoided. Good choices include Julidochromis, Neolamprologus, Cyprichromis and Tanganyikan Synodontis catfish. It can be maintained either as a pair or as a colony in a suitably sized tank.

https://www.seriouslyfish.com/species/altolamprologus-calvus/