The best thing with Africans is to either have a lot so they can't establish their own territory or provide enough space that they don't feel threatened. Most choose to pack them tight.
I ve got tons of rocks and drift wood in a 6 foot 125 gal tank with 4 juvenile bichirs. They ve got both space and a lot of holes and rocks to make it comfortable. And it's been a few months with them but every 2-3 weeks I rearrange the rock formations and add new shaped rocks to the tank and remove others so that the territory's don't get established. Also keeps me from getting bored. I did this with my 65 gal tank as well except changed scape every 4 months as it was 90% planted and just stacks of drift wood leaned on hidey hole decor. And dug out trenches.