I'd try apisto's if you want a species only tank. Could do a BONDED pair of apsitogramma panduro. Or a trio ( 1m 2f) apistogramma cacatuiodes? ( someone tell me how to spell that? Lol)if you re over the decor and such you could get crushed coral substrate. You could do shell dwellers ( look in cichlid section for info) they need 3 shells per adult and they breed very quickly