Yes, the tank is a standard 55g (48 x 13 x 21) with more than 60 shells. I have the mellow shell dwellers with the N. multies but I would like to add some diversity to my L. Tang species and provide a comfort fish so that the Sumbu will hopefully show themselves more readily. I have had cyps and would possibly entertain getting them again.N. leleupi and a N. brichardi are too aggressive for the A. sumbu shell.
Smaller Julidochromis can be compatible but I don't think they will work as dithers because they will spend most of their time hiding in the rocks.
How long is your tank? 48"? With some higher rocks and a more dim lighting Paracyprichromis might work.
Another approach that could work are more mellow shell dwellers and more shells. Normally I would not suggest species that will occupy the same habitat but I know somebody who successfully keeps the combination of N. brevis, Telmatochromis sp. vittatus shell an A. sumbu shell in a tank 32*20". There are at least 60 shells in the tank.
In both cases I would not expect any A. sumbu fry to survive.
Nice looking fish but total psycho as some people would call it. They need at minimum a 5' tank. If you want to keep more than one male 6'+.Dave's Rare fish and I find this "Ophthalmotilapia boops Nkondwe Island." BOOPS, I gotta say it the best Latin naming convention ever and I now have an irrational need to add this fish to my collection.