Depends on which type of lap. I come across nigerians from time to time locally. They look better ime on black sand mixed with some red. Here are some pictures of my nigerians. I just got the guy in the last picture last night so he hasnt colored up yet.
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Since JA left its been a bit of a struggle. Primo aquatics might be able to get some if you email. I know they delivered a spotted far for someone here w/o any issues. Aquatic day care, aquascapeonline, amazing fish, and toyin. There are eBay dealers and they have them available there. Gotta search for polypterus. I think even petzonesd had some. I'm sure if you notify a vendor they can tell you for sure.
as kn04te suggested aquascape online i was at their store the other day and saw they have a few good looking laps. for substrate i prefer the look of black sand but i also have some pieces of red slate
Aqautic day care and toyin(rehobothaqautics) are your best bet .... An 80% red with 20% black mix substrate is 2nd best .... Garnet is best substrate for them