Your display aquarium should be blacked out with a black sand substrate also. Then use rocks/driftwood/live plants for aquascape. These 2 fish will indeed grow into show fish! By his time next year you will be amazed at their mature coloration! Congrats!
I just last week sold the Firemouth that survived to another mfk'er with an Exasperatus cichlid. The one Firemouth killed the other one about a couple months after I got them. I'm not sure of the members name but he is young and always in the cichlid forums.