Conventional cichlid keeper "wisdom' suggests getting several youngsters and shells and letting them grow up together. In time a pair will usually form, assuming good water quality, water hardness (often not a problem in the US), feeding and sufficient shelter to form a territory.

However, and this is true of a lot of cichlids, a couple keys to their successes in the wild can create problems in the aquarium. In the wild a pair will form, set up housekeeping in or around a suitable site, in this case a specific snail shell, and they will chase their former cichlid companions away. In the wild that works better than in an aquarium (though even in the wild if the evicted companions can not find shelter elsewhere, they may be eaten by a larger predator.) In the aquarium, when "odd men out" are hiding behind the air filter line or the filter or are cowering at the surface, we must get them out of there or expect that the pair will kill them.

So there may very well be a need for a second tank, first for the exiles (which in time may be given away, taken back to the shop or sold at an aquarium club auction) and later for the larger fry. I've seen this with other Tanganyikan cichlids, which may form a colony of parents and young. At a certain size and population density, the larger young will be driven out (in nature to colonize other territories.) What is a great species survival strategy in the wild - the population is widely dispersed - can lead to cichlids slaughtering one another in close quarters.

So you may face that second aquarium catch-22, just as many of us have with guppies. When animals breed, that changes the rules.

Also, just as guppies are best not kept with the majority of aquarium fishes because those fishes are too big for them, so too the little Lamprologus and Neolamprologus are vulnerable to bullying by a lot of other fishes, especially other cichlids. They are best served by a single species tank.

I'm surprised that I have never purchased a group (or proven pair if I was really lucky and IF they stayed together) of Neolamprologus multifaciatus. I was shocked several years ago when a cichlid keeping buddy bought a hard water killifish (Aphanius mento) and put it with his hard water multifaciatus. The similar sized killies, which in that case do have a reputation as a fairly aggressive fish for their size, hunted down and killed every multi in the aquarium!!!

Guppies have been used a "dither fish" for small cichlids. Their presence may bring the cichlids out of hiding, but understand that another name for dither fish is "target fish."

Lake Tanganyika may be best though of as a larger tropical sea, though the mineral content is mostly calcium, magnesium and potassium, as with so many inland waters. Its temperature varies very little, so heating must be consistent.

Also, because Lake Tanganyika is one of the world's largest lakes (and one of Africa's Great Lakes), the water chemistry is pretty unchanging. They also are not very tolerant of fishy wastes in the water. Our guppies, though not the really fancy ones, can get away with neglect, which might kill the shell dwellers. Filtration must be effective. Water changes of the same temperature and mineral content should be modest - perhaps 10% a couple of times a week. They can not take massive changes or they will die of shock.

You could leave the Java moss with them. The young ones especially will enjoy it. Sand is interesting to look at, but often a lot harder to clean than gravel.  Also, once in a while some organic stuff will get trapped under the sand. If it stays there long enough, anaerobic bacteria will start breaking down the organic debris and if that stuff is not stirred up and siphoned out of the tank, nasty toxins such as hydrogen sulfide can be formed.

If you have mastered keeping the gravel clean, you probably can do fine with sand. If you have the occasional bouts of cloudy water, stay with the gravel until that doesn't happen any more. Your cichlids will be healthier.

Also if you don't dry out the gravel, but keep it wet and just move your guppies out, you may keep the nitrogen cycle pretty much going in that tank. (If you think guppies are vulnerable to crashes in the nitrogen cycle, wait until you see Tanganyikans.) Maybe you could wash some new gravel for your guppy tank. Line the tank with new, rinsed gravel, put in some water from the previous tank and then cover the gravel with a layer of the gravel from the established aquarium. With the cichlid tank, if you could pile the established gravel to the side, line the bottom with the new, washed gravel, you could then spread the wet "old" gravel over it and keep most of the cycling capacity going. You might start a second filter now in the guppy tank too (at least a box filter) so that there will be an effective filter for both the guppies and one for the cichlids.

As always, starting the new aquarium with a modest sized population is really important and profoundly increases their chances of surviving. If you have mastered all of the stuff suggested for starting and maintaining guppy tanks, the cichlids should be no problem.

The article below may well be something that you have already Googled. I'm sure you have read up on the shell dwellers. So that is mostly for the benefit of those looking on.

Have fun!