Smaller varieties of Julidochromis is a good suggestion. Pretty much any smaller rock dweller from Tanganyika can make a home in there.
You can do a couple of pairs in that tank, say a pair of Julidochromis Regani with a pair of Neolamprologus Leleupi. Others might be Neo. Caudopunctatus, Telmatochromis Vittatus, and Altolamprologus Dwarf.