Maintain a pH level of about 5.5 to 6.5. Captive fish or store bought discus fish can survive in harder water and acidic levels that can reach 6.8. They are already used to this. But for breeding purposes, stick to the natural levels that discus fish are used to. If the temperature and the acidic level falls, there will be a good chance that your discus fish will not breed and in certain cases, they can even die. So you need to have a very keen observation so that you will be able to truly determine the sex. You will need to be very patient and to follow the fish well, for those who do not know the differences between the male and the female, it would be very hard to discover its gender. Here are some points which can help you identify the gender of a discus fish. If your discus fish go on food strike, it s a clear sign that they are unwell. The color of their scales will also get darker, which is also an indication that the discus fish is sick. These are some of the things that you need to understand about discus fish. Keep in mind that you have to set up your aquarium as well as the conditions in it that mimic their natural environment. Basically, one of the most common problems among discus fish is having a hole in the head. Early detection is essential in order for you to treat them effectively. You need to remember that the longer the disease exists in the discus fish, the most probable it will be that the disease may cause its death. Discus Fish will establish territory within the aquarium and you will see them defending it against the other fish in the tank. This means that they are getting ready to breed. You have to keep an eye on the mating pair as you will need to move them in to the breeding tank. In order for the breeding to be successful, you have to get a separate tank for the breeding pair. Since Discus Fish are very sensitive to water quality, make sure that you keep your aquarium clean. 50 percent of the water should be changed every week and you have to keep the water free from chlorine and heavy metals. To do this, a water purifier will be able to do the trick. Keep in mind that Discus Fish thrives in the Amazon River basin where the water is slightly acidic and soft.