I agreed with kodyboy......Keeping the water clean is the First step, to keeping Discus...alive and healthy. Second keeping aquarium surfaces clean. Third keeping proper temp. Whether getting Discus from private seller or LFS....wild caught or tank raised check if they're using RO or not. Helps to know....too much difference will put the fish under stress. IME Using RO, you will need to add back the trace elements the RO takes out. I use treated tap water and add oak leaves or peat to my system, for lower PH. Ask what they're feeding them, saves on the trial and error method....Discus can be very picky. IME Mine like the plecocane that Tony is selling. But they love bloodworms and will eat mixed flakes. Some were raised on bloodworms, so it took a long while to get them to eat something else besides the bloodworms. If you have more questions or have problems....where to buy food or fish or anything just ask....that's what the forum is for. Good Luck