Hi Des,
I have my discus whit my plec,s. And just like you i have Apistogramma and corydoras in same tank. I have only 1 tank just now, beucose i have just move too a house and my fishroom is not finish yet.
My Zebra is not shy, they eat side by side whit the discus. They start doing that when i give away my dominant catfish from the tank.
The only catfish i wont have whit discus is sturisoma, becuse thay think discus is a free taxi, they jump on the discus for free ride
Tell please litte hove goes whit your discus, apistogramma and hypancistrus tank
Patrik