german blue rams or kribs with black sand as substrate?

[Phyrex]

I really like the look of black sand as substrate but I don't see any german blue rams or kribs tanks with this substrate, can I keep them with black sand or do they need white sand/gravel?

 

[fish-n-chips]

I have a 20 long that I have a mix of black gravel and black tms. I like how the dark substrate really makes the colors pop more so than the lighter substrates. Don't quote me on this, but I imagine that with wc fish it is more natural for them and would help to relax them and to aid in inducing spawning. These are F1 P. taeniatus "Moliwe", though. Here is a link to my album~
http://www.apistogramma.com/forum/album.php?albumid=34 . That is the only tank that I use it in, the rest are more natural or lighter colored and the fish in those tanks don't have as much color but they still look great.

 

[dwarfpike]

I have kept wild rams over a black sand substrate before, and they looked fine. Acted fine as well. I have a collection description somewhere abouts that said they were collected over a mud so dark it appeared black. German blues are darker overall IME though, so not as sure I would try it with them.

I also have an Oliver Lucanus article describing a P. taeniatus from Cameroon (can't remember which exact location off the top of my head) that had black volcanic sand as a substrate in the stream. But I've yet to try them over a dark sand yet so can't say if they'll act normally or not.

 

[Apistomaster]

Wild Rams are not normally found over black sand but the gradation of the black sand sold in the USA is actually crushed and sifted slag, a type of glass, mostly used as a sand blasting material really but it is the right size for Dwarf Cichlids and it can set off the colors of some Dwarf Cichlids well.
I have used it with Gold Rams and they really look nice over it as would all the xanthanistic forms of Apistogramma like A. cacatuoides gold/White or A. agassizi Fire Red.