If you can get a 15 gallon long - 24x12x12 (like a shortened 20 high), and a half dozen Lamprologus stappersi
, you would have the prettiest tank ever. Set up a row of rocks along the back and plant dwarf sags behind them, then put all your shells (at least 10 for 6 fish) out front. That'll keep the fish from messing with the plants. Use coral sand or silica sand with coral in the filter. Escargot shells are the perfect size (though the nanny state won't let you sell them for food use in this area anymore - grumble, gripe, kvetch) but Murex shells have been working for me (got them from a craft store), and tulip shells are more or less the same shape as the snails endemic to Tanganyika.
You might be able to do the same thing with Lamprologus ocellatus (which are easier to find), but they're more aggressive, so be ready to bail out the extra fish if there isn't enough territory for everybody (though a 15 ought to give enough footprint for at least 2 pairs, 20 long for three almost guaranteed).