First of all there are many kinds of shellies. Some get along better than others.
It would probably be easier to just have one kind of them, some live in colonies and arent as territorial. If you keep several kinds in to small a tank the more agressive kind might take over.
Plus they will be competing for the same territory (the shells).
This sitee has some short facts on most tanganyikan fish:
http/www.riftlakes.com/
Just select english at the top of the page. Then tanganyikan
Info on multifasciatus:
Trade names and synonyms
Neolamprologus multifasciatus.
Size
This is one of the smallest cichlid in the world. The male could reach a maximum size of 4.5 cm (1.8 in.) and females 3 cm (1.2 in.).
Food
Shrimpmix, spirulinaflakes and brine shrimps.
Aquarium
This cichlid could be kept in small aquariums, I would recommend a size from 50 litres and above. This is enough for a small group of fishes assumed that you have enough of empty snail shells in the aquarium, at least one shell for each female.
Arrange the aquarium with fine sand and lots of Neothauma-shells or any equivalent shells.
Habitat
<Lamprologus> multifasciatus is found at sandy floors covered by empty shell from the Neothauma tanganyicense snail. Like N. brichardi it is living in groups and the main feed are plankton. Each individual has got it's own shell.
Breeding
This cichlid is very easy to spawn, the spawning take place in empty shells.
If they get on well they could get between 5 and 20 fry's every third week.
The male usually spawns with several females, therefore he will have a large territory which he guards with success even towards much larger species.
General
<Lamprologus> multifasciatus is my favourite cichlid in all categories. The interesting behaviour, the size and simplicity to get it to spawn makes this cichlid to something special.
A perfect cichlid for those who ain't have the room for a big aquarium but still wants cichlids with interesting behaviour.
They are great diggers and they push the shells around the tank.
Could be kept in separate aquarium which only contains this species but they also fits well in a community with other tanganyika cichlids.