There are two main 'types' of Discus, wild and captive-bred. Captive-bred discus are hardier and more adaptable to a wider pH range, plus they come in an array of colours and patterns such as Snakeskins, Red turks and Blue turquoise.

As Fishyfins has said you can keep these fish with others or just by themselves. Suitable tankmates include smaller characins (do your research however as some are known fin-nippers), catfish (i.e small plecs and corydoras) and Dwarf cichlids (i.e apistogramma, keyholes).

RO (reverse osmosis) water is highly recommended due to it's purity and low pH however it will need to be re-mineralized before it is added to the tank as RO water in its pure state will send fish into what is known as 'osmotic shock'.

I would highly recommend large pieces of bogwood for hardscape, Sumatran driftwood also looks very effective and both will help to lower the pH of the water. In terms of plants Vallisneria is hardy and makes an excellent background species, discus look absolutely fantastic against a thick backdrop of this plant. Other species to consider include Amazon swords (Echinodorus amazonicus), Cryptocorynes and Sagittaria. Take a look at Tropica