Water chemistry is one of the most important factors that you need to understand when you plan on raising discus fish. With proper water chemistry, you can be sure that you will be able to keep your discus fish healthy as well as happy. As a discus fish owner, you need to understand that you should test the water prior to every water change. As much as possible, you should buy an adult Discus Fish. This is highly recommended for first time owners of Discus Fish as adult Discus Fish costs lesser to maintain than juvenile ones. You need to remember that juvenile Discus Fish are far more sensitive to water quality and food quality than adult Discus Fish. This means maintaining the temperature and the pH level of their water. Discus fish tend to get stressed when the water experiences an abrupt change or if its dirty. The Don ts Don t allow your tank water to get dirty and filled with food debris at the bottom. Any debris left can cause bacteria to develop and make your fish ill. Unlike other types of freshwater fish that you will often see in retail chains, Discus Fish will require you to pay close attention to them in order to keep them healthy. But, you shouldn t let this fact intimidate you and scare you from owning this kind of fish. With the right knowledge, you will be able to maintain this beautiful fish for many years to come. So if you plan on buying a smaller tank know and just upgrading to a bigger one later on, you may find that this would be futile. You would just be spending more in a short period of time. A small tank will just stunt their development and will stress them out. But also remember, if the tank is too big, the young discus fish can become overly skittish and can also stunt their growth. 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.