hmmm there is many you could do.
Shellies are really cool & fun. The demasoni idea can work but tank needs to be packed with hiding places. Actually I had the best breeding & less death packing about a dozen of these meanies in a 20 high. I have & breed paracyprochromis niggripinnis or another type of cyprochromis type? Electric yellows or rusty small young group can work also. the Julies also can work.
Crazy things can happen, I have a Pair of Zaire frontosa breed in a 27 long & the babies are still in there swimming around.
me Dave