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Discus showing signs of being infected with the "Discus Plague" virus.
By Tony Griffitts
The Discus Plague is a term often used to describe a common Discus disease, where Discus show the following symptoms:
- Dark background color
- Clamped fins
- Hiding in a dark corner in the tank
- The body mucus is visibly heavy, and often comes off the Discus
It appears this disease is probably caused by a virus, and there is no known cure. This disease only affects Discus. It is not all that uncommon for all Discus in the tank to come down with the disease, except for the new Discus that were introduced sometime 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 from tank to tank. Just having two tanks in the same house that don't even come in contact with each other will often be enough to see it spread. It seems that the virus can go airborne, or maybe just putting your hand in one tank and not properly cleaning your hand before you stick it in another tank will cause it to spread. This disease is like the flu in humans, it will run its course and then your strong healthy Discus will recover. This disease will often kill small and old Discus. It is not all that uncommon that the discus hobbyist will loose half of his discus to this disease.
During the time the Discus have the disease they will still eat, but not as vigorously as when they are feeling one hundred percent. I recommend that you reduce the amount of food you feed them during this period to prevent any unnecessary pollution.
I normally don't do anything except frequent water changes (50% or more daily) for this disease. Frequent water changes will help reduce the organic load in the water column and increase the oxygen carrying capacity. Any attempts to medicate do nothing to cure the disease. Adding medication to the aquarium may cause more unnecessary stress the Discus can do without. This disease can take up to three weeks to run its course. Once your Discus are looking normal again, they will have some immunity to the disease for a while.
After your Discus have had the disease I would not recommend adding any new Discus to the aquarium for at least 6 months. If you add a Discus before then, you run the risk of the new Discus coming down with the disease.
I see this disease most commonly in Discus that are imported from Asia. The process of getting the Discus from Asia to your aquarium store is a multi step process. The Discus normally 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. It is most unfortunate that the fish go through this process, because this is normally how the fish end up with 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 domestically bred Discus.