The discus plague is a term often used to describe a common discus disease, where discus shows the following symptoms:
A virus causes discus plague disease, and there is no known cure. Discus plague only affects Discus. It is not uncommon for all discus in the tank to come down with the disease, except for the new ones introduced in the last two weeks.
Discus that have had the disease can be a carrier of the virus. This disease is highly contagious, and ultraviolet sterilization does little to prevent it from spreading. Having two tanks in the same house will often be enough to see it spread. Improperly cleaning hands between systems cause cross-contamination, or having systems close, allowing micro water droplets to spread between systems.
This disease is like the flu in humans, it will run its course, and then strong healthy discus will recover. This disease will often kill small and old discus. It is not uncommon for the discus hobbyist to lose half of the discus to this disease.
When the discus have the disease, they will still eat, but not as vigorously as when feeling one hundred percent. Reducing the amount of food fed during this period will prevent unnecessary pollution.
Hobbyists should do frequent water changes (50% or more daily) while expressing disease symptoms. Frequent water changes will help reduce the organic load in the water column and increase the oxygen-carrying capacity. Attempts to medicate will not cure the disease. Adding medication to the aquarium may cause more unnecessary stress. This disease can take up to three weeks to run its course. Once the discus looks normal again, they will have some immunity to the disease.
After your discus have had the disease, it is not recommended to add any new discus to the aquarium. If you add a discus, you risk the new discus coming down with the disease.
This disease is most common in discus that go through the wholesale chain. Getting discus from Asia to your aquarium store is a multi-step process. Discus usually goes through 2 or 3 wholesaler hands before they end up in the aquarium store. In this process, the discus have several opportunities to be exposed to the virus. Unfortunately, fish that go through this process often get the disease. The discus that are produced in Asia are among the best in the world. It's the process of getting them to your local aquarium store that makes them a risky buy. For this reason, it is always safer to buy all discus direct from a breeder.