Corydoras and other fish sometimes get disease. The main reasons are either not to keep water clean or to bring bacteria and parasite with purchased new fish. If you think that water is clean apparently, the water condition may not be good for fish. That is, it's extremely important to know how much chemical materials are in water. You might need to think the following chemicals: Ammonia, Nitrite, and Nitrate. These substances always exist in your water tank, but you need to keep these concentration down. When you get a new fish, you should not put water with fish to a tank because the water comes from a fish shop, and it might be included bacteria and parasite, which cause disease fish. If you have a tank for medication, you should use it for not only avoiding bringing such causes of disease but also stabilize a health condition of new fish . The 5 and 10 gallon tanks are the best for that because most medicines are based on these volumes. Medication is one of methods that you surely prevent disease from your lovely fish.

        Even though you care for both a health condition of fish and a water condition, fish might get disease. The causes of such a disease is due to the lack of information about fish and immature experience. If your fish are sick, the significant aspects are to find and cure sick fish at the first stage and to medicate with the proper medicine. The following information in terms of disease is not mature and not complete, but I hope that it is useful for your fish as the fundamental information.