Tank mates ?

I am sure you could find some that would get along but their water parameters and overall enviroment are much different.

Not a good mix geos like soft acidic water whereas Africans like hard Alkaline water. I have heard of people mixing south americans with Africans with success but it never worked out good for me.

I dont know about geophagus but malvais are very aggressive, i had a 3'' malvai with a 4'' gt, the malvai was giving a good beating for him though gt was fighting back..

Geos are too peaceful to be kept with malawi cichlids.

Agree. Water's not really the problem. I've successfully kept all my fish in the mid 7s pH, moderate hardness for years, including Malawis, Tanganyikans and SA, including some wild SA. But typical Malawis will be too much for most Suriname type geos-- would have said so based on experience keeping them separately, but, in fact, I had to do it temporarily last year due to a long power outage that had me juggling things after the derecho storm last year and the geos were not happy. I'd expect the same for Satanoperca.

Brazil type geos, don't know, maybe with haps and peacocks (not mbuna), though not something I'd do. Another issue is typical Malawi cichlids do better when overcrowded by SA standards.