I don't know that they'd be durable enough to withstand adult A. calvus. I have them in a couple tanks here. They don't harm plants, and stay small enough to not outgrow most tanks. They do get rambunctious and love to terrorize cories when they spawn, but I've not tried them with Tanganyikan cichlids. Tanganyikan eels, yes, hehe.
They're great fish. If you have room, get more than 5 or 6. They love to be in herds and will school around the tank.
Once the Calvus mature enough to form a pair, the other 4 will be removed. Calvus don't move around much...they remain motionless and poised to strike any prey that might move. Their pray are newborn fry the size of a grain of rice. Everything else they ignore.