I acutally live in Auckland. I do have discuss and that is how I treat them as well. I just did not want to give advise before ndrestanding what you have done first.
You are right, discuss are jumpy but once they settle down, they are very good and relaxed. you have to stop introducing new fish to the tank. that will definalty have an effect.
The size of the fish is also important, I have simmilar size fish in the same tank and it helps and of course it also depends what other fish you have in the tank as well.
I have only discuss now and some Bristolnose.
Good luck with the fish.
Regards
Tofigh