External Hexamita

Internal Hexamita

The external form of Hexamita is referred to as: Hole in the head disease.  This disease affects susceptible fish such as discus, angelfish and oscars, which seem to be the most popular carriers of this problem (note that this disease may affect all fish).  This disease usually starts out as a small "pimple" on the head, and as the condition proceeds in severity, ends up to be a very large sore causing lesions in the epithelium and... eventually ending up in death of the fish.  Sometimes you are able to see small white nodules, sticking up out of the sore.  The lateral line is also another area where this parasitic protozoan can be seen.

This disease is best treated early on with Metronidazole, or something stronger like Quinine Sulfate.

The internal form of Hexamita are flagellated protozoans found in the gastrointestinal tract of a wide variety of fishes.  They frequently infect discus.  Spironucleus may be a distinct organism from Hexamita, as it is longer and possibly more sinuous, but for practical purposes, both organisms appear to cause similar clinical responses.  These parasitic protozoa are very motile.  The flagella are usually not easily seen.  Many times infections are not apparent.   In angelfish, discus and gouramis, the disease is characterized by poor condition, weight loss and death.  The fish may also show excessive nervousness, turn dark in color, and hide in the aquarium. 

Again, Metronidazole  is the drug of choice for internal Hexamita.  Use 1 teaspoon per pound of food (frozen food is preferred).  Thaw the food and mix the Metronidazole into it.  Return the food to the freezer, and once frozen you are ready to start the treatment.  Feed it to the fish once a day for a minimum of ten days.  Do not feed the fish any other foods during this treatment.   The treatment may take longer according to the condition of the fish, and the severity of the disease.


Metronidazole is for internal Hexamita, and the Quinine Sulfate is for external Hexamita only.


Best Regards,

Dr. Gary Aukes; Pharm D, Dr. Brian Aukes; PhD., and the staff of National Fish Pharmaceuticals.

Fish Disease Articles

Items that can be used to treat the diseases listed in this article include:


Quinine Sulfate

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