I am in the process of learning much more about Discus. So I will be following along too.
They like higher water temps and I know Cardinals are often tankmates with them. Careful selection of plants is required as certain plants do not do well in higher water temps.
They require extremely clean water, with pwc
on daily to every other day basis. Which atm is why I won't be having them in the immediate future. Like fresh, live foods too. They are a lot of work from what I have been finding out!