Tank Size for Discuss? (non breeding pairs only)
I agree about the 15-20 gallon ratio per discus. BUT this does not mean you can keep one discus in a 20 gallon tank. Discus do better in groups. Being shy, nervous fish, they feel better in bigger numbers. Plus having a larger group, means less aggression.
Best tank mates if any?
I would have to think most peaceful community fish. Angel's are closely related to the discus and are more aggressive eaters, so depending on the eating habits of the discus, you may/may not be able to keep them in the same tank. I have discus and angels in my 125 gallon (473 liter) tank and luckily for me, my discus are as aggressive eaters as the angels. I have 5 clown loaches, L-018 Gold nugget pleco, L-260 Queen Arabesque pleco, 4 angelfish, 6 harlequin rasboras, 2 rainbows, and 7 various cories in my 125 gallon (473 liter) tank with my discus.
Temp?
Discus do better in warmer temps. I keep mine at 82°F (28°C), which the discus are doing fine with. I know most people prefer at much higher temps.
PH?
Tank bred discus have been bred/raised in varying pH levels. Mine are currently in a pH of 7.2
Food for them?
Best to give them a varied diet of frozen food. Although I know many breeders like to feed discus red wigglers, I like to stay clear of live foods, since there maybe a chance the discus could pick up some kind of internal parasite. I feed mine frozen blood worms, frozen mysis shrimp, beefheart mix, frozen brine shrimp, hikari sinking carnivore pellets, tetra bits, frozen peas (skinned). My discus will ONLY eat the frozen peas if I hand feed it to them, otherwise if I just drop it into the tank, they will not even look at it. I know, I spoil them too much.