Discs can definitely be difficult. I currently own a breeding pair - a gift from the owner of the lfs (whose kids I seem to be putting through college!) - and they make my beloved Angels look like child's play. They require twice weekly water changes, can be extremely temperamental, and definitely need looking after. Where my Angels never seem to get sick (knock wood) I've had a pair of bouts with intestinal parasites in my Discus in only 6 months (resolved thanks to Metrozol, but only because I knew what to do ASAP). Moreover, they definitely eat smaller fish - their tank has held a total of 21 ghost shrimp - all of whom disappeared with startling rapidity, despite the fact that both Yeti and Sasquatch are fed three to four times daily, on a diet of beef heart, bloodworms, and assorted flakes. In addition, Discus seem prone to personality disorders on a large scale. No problem if you know how to deal with them, but an issue if you don't. For example, Sasquatch decided almost instantly that while Otos were acceptable tank janitors, Cory cats were the minions of Satan himself and had no place in "His" tank. I therefore had to remove four of the cutest little kids you ever saw (to other tanks) - leaving Yeti and Sasquatch alone in a 110 liter with ONLY a pair of Otos and the first of many ill-fated trios of Shrimp. Definitely not a beginner fish, and definitely not one I'd plan to move in with a larger fish, mostly because the Discus may not agree with your rooming plans. However, as DM suggested, if you do a little research and think you're ready for the challenge, they're definitely characters and very easy to become attached to.
I started with Discus on a whim and had, according to other articles I've read, some blind dumb luck. I've had one of 10 die from an intestinal blockage, but other than that, my pet store Discus have all matured into beautiful healthy fish. They all have unique personalities; some shy, one ill-tempered, the rest friendly and becoming tamer by the week. They recognize me and ignore my husband (because I feed them, I suspect). I do not plan on breeding them - I'll let them handle that if they are so inclined. Unlike myself, you should spend $10 and do a little reading from a book on Discus basics and then plunge in if you've had at least one successful aquarium. Just allow at least 40 liters of water for each full grown fish and try not to overfeed them. They are excellent beggars, so it's really hard to ignore them when they are "profiling" you at the front of the tank to convince you to bring them some food. Good luck!
The discus is also known by its fanciers as "the king of aquarium fishes". The title is quite right, this majestic creature is amazing. OK, I know for saying this next line you're gonna say "huh?", but here goes: Discus are NOT that difficult to keep. There I said it. But really they aren't, they just have specialized needs that must be met for the fish to thrive. They are quite adaptative too, I get a lot of my discus from a fellow breeder who keeps his pH at 7.6. I keep mine at 6.5 so they have quite a swing when coming here, but they adapt just fine. They do need twice weekly waterchanges of 25%, good filtration, and a great diet. I feed them tetra min flakes, freeze dried bloodworms, frozen krill, frozen bloodworms, spirulina flakes and hikari discus pellets. Also my homemade frozen beefheart mix. They need high temps 29-31°C, I use 30°C. Most people say 40 L per discus, but I use 60 L per discus, they love the extra space. IMO breeding pairs should be housed in large tanks.
Discus are not for beginners. You should at least understand water chemistry before trying them. They're not all that hard to keep though. They are just a high maintenance fish that need attention, and should not just be kept, but rather pampered. If a Discus does not get fed a varied diet and gets water changes once a week or worse, the result could be a stunted fish that hasn't grown full potential. One that is pampered, however, grows to full size and overall looks much better. With these fish there is no such thing as too many water changes.
Wow! The stories about Discus cover quite a range of experiences. I had read and heard that Discus should be reserved for experienced fish-keepers, so we held-off awhile before setting-up a 200 liter (3) Discus home. We've had the "big aquarium" going for about 9 months now, and have since set up a 150 L tank with 2 Discus. Between the two tanks, we have 3 Turquoise and 2 Pigeon Bloods, and have had absolutely NO PROBLEMS with out Discus. The pH in the larger tank is around 6.6-6.8, and closer to 6.0 in the smaller tank. I am lazy about water changes, and usually get to it once every three weeks (I know...I need to do better), but the Discus don't seem to mind. Both tanks are very heavily planted with thriving live plants. Some will groan and some will sigh when they hear this. The 200 L tank has several other fish in it, and everyone gets along just fine, mostly a happy family, but the plants are so thick, nobody HAS to deal with anyone else if they don't want to. I feed everyone OSI flakes and frozen spirulina-enriched brine shrimp, plankton, mosquito larvae, and daphnia. The funny thing is, I've had an impossible time with Blue Rams (gave up!), Apistogramma McMasteri, Neons (go figure!) and even Apistogramma cacatuoides. So, there you have it...trouble-free Discus at this quarter. We love 'em. We've even had a first-attempt spawn in the larger tank. Our Discus mostly eat like PIGS. I believe that much of our success is due to the fact that we have great soft well water that can go straight into the tanks without any treatment, and our tanks grow plants very well. I have to harvest cabomba twice weekly, and Java Moss monthly to maintain swimming space. Maybe it's the water or maybe it's luck, but Discus have been easy for us.
I have 16 Discus in a 600 liter tank and they are so well coloured and healthy that many of my friends are wanting to have Discus themselves. A lot of people say they are so hard to take care of, that's not true in my case! For 2 years I've had Discus and only have lost 2 due to a stomach infection from the fish shop. If you have a brain, the time and the right equipment, you can have discus and keep them in excellent health. Any problems I use melafix and geo liquid, they help make my Discus look in excellent form, as well as a 20% water change twice a week. I feed them frozen brine shrimp, blood worms and Tetra Bits discus pellets, they go crazy for all of these. If you want more excitement teach them to eat out of your hand, that's a real treat!