Guppies need hard water, Discus prefer warm, soft water, so the two should never bump into each other in an aquarium. Dogfather is right, neons come from cooler waters and neither fish will be really happy at a compromise temperature.
I think the electric blues and yellows you refer to are African Cichlids, and require very different water conditions.
Good fish for a Discus tank include:
Apistogramma species
Cardinal tetras (not very small ones!)
Good quality rams (bolivian are hardier and nice in a more subtle way than the weaker blue ram)
Clown loaches
I wouldn't add just two if they are not a breeding pair, one will get bullied. Three is also a bad number, as the weakest fish will be bullied by the other two. You should aim for at least 5 juvenile fish (at least 3" long) and let them grow on to near adulthood when you should be able to pick out a pair and sell the remaining fish if you dont have room for all the adult fish when they mature.
can any1 give me some info and tips, and what to never put them with?
The problem is, many people will tell you to avoid other fish altogether! If you get Discus, be prepared to put them first at all times. They are quite tough fish, but will not tolerate you sorting out the problems of other fish in their water. Basically, if the Discus are not sick, never treat the tank. You will need to remove any sick fish to a treatment tank, and keep the discus tank as stable as possible. Large water changes with un-controlled tap water can be a disaster for Discus if the water is not up to their quality standards, chemical warfare with all sorts of medications is worse!
The main point is, when you keep Discus with other fish and plants, the first question you need to ask yourself before doing anything (no matter how small) is, 'How will this affect the Discus?' If you prefer not to be basing all your decisions around just one or two of your fish, then Discus probably are not what you are looking for.
Ken
