one of the key things with discus is that they like a lot of clean fresh water, so in general you need to do more water changes than you would with other species or a community tank. Also they tend to do better either with other discus or specific species, ie cardinals, etc, they are slow eaters, and prefer warmer water than a lot of other tropical fish so most aren't suitable to have as tank mates, eg, swordtails, angels, gouramis, saes etc