I presume you are talking about Auchenoglanis occidentalis? If so these fish grow to around 36" and would need a 8x3x2' tank at least. There is a nice Dwarf species (Auchenoglanis macrostoma), however, these are often difficult to track down.
Even in a large enough tank the girraffe cats continual digging and searching for food would spook the discus. Discus need small quiet tankmates like corydoras and appistogramma dwarf cichlids.