Well, if you want to stick to the African oddball theme then the only other surface dwelling fish I can think of would be African butterfly fish. Microctenopoma ansorgii could work too but I'd be worried that some of the larger fish would eat them. They are also fairly rare so you might have a hard time getting hold of them.
Wow I've never seen an ornate ctenopoma but they're cool looking. I'm fine with the standards, I guess there really aren't a whole lot of choice of other fish to work in this tank. Definitely no rift lake cichlids, the only other fish I can think of would be Jewels and Kribensis.