All cichlids are chameleon like, and will try to instinctually blend with the substrate to make themselves less obvious to predators.
So if you put in a white substrate, with white rocks (unless you add dark sunken logs or some other dark decor such as lots of plants), don't expect darker colorful fish to show normal colors.
As an example of a cichlid that will show great colors on light substrate (because it is the norm in their habitat in nature), Herichthys carpintus is a good choice
Most danger to themis not lethal and un-notuced from the side, and fish "want" to be noticed by potential mates.
Their primary predators are aerial.
So this broadside color is desired, but from the air, their coloration makes them almost invisible.
There are 3 capintus in the pic below.
But even in this case, the substrate is "not" un-naturallywhite.
Another problem with stark white substrate is, your cichlids will want to constantly hide.
Many fish have the ability to color shift in an instant, even the mollies in the video below
Eden2
But also notice the JDs, that lose color over light colored substrate toward the end of the video, compared to the ones in the beginning, or living at depths.
If you want your cichlids to show great color like the way they do in nature, providing the color substrate that most matches their natural habitat is the key.
