So the unthinkable happened.
My discus produced a clutch of eggs.
What's more, two of the angels were in the middle of laying their own batch at the same time.
Unfortunately by this following morning they were all gone (in fact the angels were eating their own eggs as fast as they laid them

), but I'm just amazed that three species now reproduced in my system, including freaking DISCUS. The conditions I provided must just be that good.
I briefly entertained the idea of making a new setup just for the discus pair, but they weren't the most expensive type out there ($90 each, when higher end ones go for multiple hundreds) and by the time I went through all the hassle I probably wouldn't break even. Still though, can't believe I've gotten what's widely considered the coupe de grace of freshwater fish to breed, without even actively trying.