Updated 3/12/10

Ichthyophonus (Ichthyphonus) fungi are one of the more devastating aquarium diseases. It is nearly impossible to treat, however it is easier to prevent.
This disease may be more common than many aquarists realize as identification is often very difficult with the proper scientific instruments and a Necropsy of infected tissue such as the heart or brain.

A few possible outer symptoms include:

• Ulcerated small nodules in the skin
• Bulging eyes (from pressure exerted from the infection in the brain)
• Loss of color (similar to Neon Tetra Disease)
• Loss of energy (due to the infection in the heart)
• Whirling; this is a very common symptom that unfortunately usually is one of the final symptoms due to infection in the brain (although this symptom can appear early and be the first symptom)
• Often Fish suffering from a systemic aquarium infection of Ichthyophonus will die off at irregular intervals, which often makes disease identification difficult.
• Sudden cooling of the water can be allow this disease to go systemic as Ichthyphonus fungi are generally more virulent in colder waters, so this can also be a "symptom" since actual tests are impossible to conduct in live fish (see lower in the article).

The picture to the left is of a Salmon Heart, cut open to show the Ichthyophonus nodules.

Please click the picture for a better view.







Ichthyophonus generally affects fish as an internal fungus , often attacking vital organs such as the liver, kidneys, brain and also the muscles on occasionally. The result is often a deteriorating fish that often stops eating (making medicated foods useless), swimming in circles (loss of equilibrium caused by the infection invading the brain), and loss of color and scales.


The above picture shows the infected heart of an Alaskan Salmon.

Potential treatments are Methylene Blue Baths or Potassium Permanganate Baths, increased salt levels (for fish that will tolerate this) of from 1 -2 tablespoons per 5 net gallons. Some Organic Treatments such as Pimafix , Kanamycin combined with good electrolyte and calcium levels measured by a GH over 100 ppm can help as a cocktail. A Medicated Wonder Shell would aid this cocktail by adding more anti fungal treatment along with adding important electrolytes and calcium. Other measures for possible treatment (or more to check the spread) are heat as Ichthyphonus fungi are generally more virulent in colder waters, so raising temperatures above 82 F (28 Celsius) can at least aid in checking the spread.

One very potent treatment “cocktail” (combination) is the combination of ParaGuard with Kanaplex and Nitrofuarzone (Furan 2). Please note that this combination is a potent treatment and water parameters should be monitored carefully during this treatment (usually about 7-10 days). This should be used in addition to the before mentioned baths (with Methylene Blue or Potassium Permanganate) and water parameter corrections (if necessary).

However all the above is often in vain, with the one bright spot that these procedures along with UV Sterilization will often check the spread of this disease. Other important preventatives is too remove suspected fish to a quarantine tank, in fact I strongly recommend this (or simply euthanizing them) as this is commonly spread through the eating of infected fish’ waste by otherwise healthy fish.

Prevention of Ichthyophonus is definitely the best cure.

Here are a few preventative steps:

• Quarantine or at least give 30 minute medicated baths in Methylene Blue or Potassium Permanganate.
• Keep optimum water parameters for the fish you are keeping whether FW or saltwater.
For freshwater this includes ammonia/nitrites at 0, nitrates below 50 ppm, a stable pH, and positive ion mineralization for the fish kept (a GH of at least 100 ppm, often higher for many fish).
• Regular cleaning procedures
• UV Sterilization
• Treatment with Malachite Green/Acriflavin/methylene blue based products (such as Medicated Wonder Shells) or Aquarium Pharmaceuticals Fungus Treatment after suspected Ichthyophonus carrying fish die or are removed.
• Increase salt in aquarium, at least temporarily to the highest levels the fish will tolerate.
See this article for more about salt use: Salt in Freshwater Aquariums
• Change your source for new fish, this is not to say that your trusted aquarium/fish store is always a poor source for new fish, however this needs to be ruled out since this disease is generally introduced and often I have had clients with unknown die offs that fit the description of Ichthyophonus, keep having problems with this disease after bleaching the aquarium and re-starting, only to buy new fish from the same source to repeat the problem; often when the source of new fish was changed after a bleaching/sterilization of the aquarium did the disease problems end.

Please read this article for more about aquarium disease prevention:
“Aquarium Disease Prevention”

Please read this article for more about studies of Ichthyophonus in Salmon:
“Ichthyophonus Disease”