Males will grow 14”+ and they are typically belligerent, especially with similarly-shaped cichlids. In most cases if they are comfortable in their surroundings they will want to rule the tank. Up until 5” or so my group was fairly tolerant of each other and other cichlid tankmates, but then that started to change.
Personally I would only keep them in very large tanks (125 or 150 gallon 6’ tanks at a minimum) with other sturdy, large-growing stuff. Mine did okay with an 11” pair of Heros liberifer and large geos like winemilleri. It hated chocolate cichlids, and tried to eat some smaller lugubris pikes that I added at 5” or so, going so far as to try and dig them out from under the driftwood they hid under. I eventually had to remove them. Since those are thin and noodle-shaped like bichir, it might mean they’d view bichir similarly if they were too small.
I definitely don’t think I’d keep them with discus unless the tank was truly huge. They will out-compete discus for food every time.