This disease is most often observed in discus, angels, uarus, severums and oscars. Fishes infected with Discus Plague will lose their natural coloring, turn dark, and become reclusive, huddling together in a dark corner of the tank. Heavy mucus secretions on the skin, accompanied by severe fin rot, scratching or rubbing against objects in the aquarium, and rapid breathing are also characteristic symptoms of Discus Plague. Upon close examination, the fins of sick fish may exhibit clear, non-pigmented areas where the tissue appears have dissolved. The mucus layer will also appear streaky where the fish has been rubbing against objects. Even though infected fishes appear to be very sick, they continue to eat, although sparingly. When feeding, they move in a tight school to the food, and retreat together to a dark corner. Some fish may even lie horizontally on the top or bottom of the tank, trying to hide in the merest shadow!
Due to a bacterial infestation from any or all of the following bacteria: Hexamitiases, Pseudomonas, Streptococcus, Chondrococcus columnares and Aeromonas. This disease is typically introduced into an aquarium by a new fish, plants, decorations, or live food. The carrier is usually not a sick fish, but rather a healthy fish or plant from a tank which harbored the disease in the past. Fish will begin to display the symptoms described above within 3 to 5 days after exposure. Mature adult fish appear to suffer the most severe symptoms, often dying within the first few days of the disease.
Effective medications include the antibiotics Chloramphenicol, Tetracycline, Oxytetracycline or Gentomycin. These will quickly arrest the fin deterioration as well as reduce the mucous production on the skin. These drugs will not, however, cause sick fish to immediately regain their natural color or cease any "huddling" behavior. Within 7-21 days, however, these symptoms vanish and your fish will reappear at the front of the tank, looking for food.
Concurrent treatment with oxidizing agents, like Potassium Permanganate, will help to keep the bacterial count down (which will aid your fish in its natural fight against the infestation). Controlling the temperature of your aquarium has also proven to be effective in the treatment of Discus Plague. Try to keep the temperature of your aquarium or hospital tank in the 85-90 F range, if your fish can handle it. A low pH (5.5 - 6.5) may also prove helpful as some bacterial species are not able to withstand an acidic environment.