I'm no expert, but I believe most chichlids are territorial and aggressive; you may need a lot of bottom surface to keep them with big bottom dwellers (Both Clown Loach and Black Ghost Knife get huge -up to 18 to 20 inches in lenght- and despite being kind of shy, I don't know about Clown Loaches, but the Black Ghost Knife is territorial). Providing good hiding places (e.g.
PVC tube caves) might help a lot.
Note: Black Ghost Knife will need more than 4foot long tank when adult, so a 6footer might do it.
Could you be more specific as for which chichlids are you into? African or Central/South American? Some chichlids will NOT share their tank at all, some will give you a few options but with others it might work out. Interesting stocking idea.
Some guys here have a lot of experience with chichlids, I would check back on this thread to learn about this. Thanks for posting
Pepe
Santo Domingo