Changing the water in your tank should be done at least once or twice a week. A partial change will also be good and it will require less handling of your fish. Changing at least a quarter to half the water in the tank will suffice as long as you have a good biological filtration system installed. In some cases, some aquarists would just add some medication to clear up the dirt. You need to be able to mimic the waters of the Amazon River in order for you to properly care for your discus fish. This means that the water should have an acidity level of pH 6 and it should also be soft water. These are the things that you need to remember when you are planning to keep discus fish as pets. Also, you need to monitor the quantity of heavy metals, nitrites, nitrates, and ammonia in the water. It is highly recommended that as a discus fish owner, you need to use a reverse osmosis filtration unit inside the fish tank where you keep the discus fish. This is quite advantageous and will make it easier for you to maintain the quality of water but they are not really considered as a necessity. Discus Fish that tends to stay on top of the tank or near the surface is a sure sign that they are sick. You should also look out for bloated gills as well as unusual spots. Also, be on the lookout for parasites hanging from the fish. You should also stay away from tanks that have a DNS label on them. All the work though, and the expenses, come before the fishes arrive. Like fishes taken out of the water, well, literally fishes that are taken out of the water, your discus fish will need a tank where they will live on. Unless you have a river flowing through your house, the fish tank or the aquarium will be your discus fish home for the rest of its life. Keep in mind that Discus Fish thrives in the Amazon River basin where the water is slightly acidic and soft. So, keep the PH level of the water lower than normal. You also need to make sure that the aquarium is away from doors that could open. This is to prevent your Discus Fish from getting stressed.