Discus can take a while to adjust. And a healthy discus can go as much as a month without food. Its not good for them though. But watch out for parasite!
When you buy bloodworms, be sure to get the ones that are garenteet parasite free. I get EXCLUSIVLY Hikary Bio-Pure frozen bloodworms.
A good way to get them interested in food is live brine shrimp. But again, you have to watch out for parasites and contaminated water. I do not normally feed mine live brine. Too risky.
Also, I order live California Blackworms for mine as well as the bloodworms. However, EXPECIALLY with blackworms, you want to make sure to get them from a reputable producer who takes care of the worms. I used to get them from an LFS that ordered them from the same place I did. And paid for it the hard way. They did not care for hte worms, and the worms were basically pure bacteria.......
And be very carefull with beefheart. Some of them LOVE it, some of them HATE it, and it can really foul a tank if they don't eat it. Been there, done that, have hte scars to prove it..... Only my wilds with touch the stuff. But thats not saying much. Those pigs eat even flake.......
I currently have 4 adult discus who seem to have paired off (one pair is "praying" to thier breeding slate every day.... but have't gone and done it yet) and 6 wild discus who are medium sized.
If care is taken with the water quality, they are a very rewarding fish to keep. But what I have learned the hardway is that Discus are very sensitive fish. Hexamita is a big worry (I would treat for this in hte whole tank, as many fish carry it and aren't harmed by it, but it will kill discus). Other parasite are a worry. Bacteria is a worry.
I like to give people headsup on some of the pitfalls of keeping discus. After I lost a whole tank of these beautys, I gave up on them for several years before I tried it again. Its going MUCH better this time around.
Hope this helps,
Amanda.