Any would do great. I think some Wild strain agassizii, maybe the
Tefe form would look good, but maybe my choice would be either;
Apistogramma nijsseni, the Panda Dwarf cichlid. The male's a blueish colour, but the female is bright (almost fluorescent) yellow with dark black brooding patches. And yet, it doesn't look artifical to me and it's a wild species. I really loved those when I kept them.
OR
Apistogramma trifasciata. This is a blueish colour and the males have extended dorsal fins.
To be honest the only ones I'd probably avoid are the artificial line bred varieties of A.cactuoides and A.agassizii as they look a little over-done, if you know what I mean. Great, gorgeous fish, but maybe not for as natural a scape as this?
For a great supplier of the more unusual ones Peter Lovett has a great range of them at
Dwarf Cichlid Aquatics I've ordered from him before and got some great Apistogramma eremopyge (which would be another great choice too!) and will be getting fish from him again soon.
