I like the polleni idea. If you are willing to order, Rapps has all the various barred amphs. which stay pretty dark. Like amarillo and barred sagittae.
Right now there seem to be a lot of Tetracanthus (Cuban Cichlids) available around the US, but if you have problems finding any, send me a PM. I have 1.5-2" juveniles from the father in the picture.