Hole in the head disease (<i>Diplomonads, Hexamitiasis</i>)


Fish show hole in head
Typical hole in the head is often seen in Discus fish.
Abnormal swimming - streaks
Fish swims in short bursts, then stops.
Dark pigment on head
The head of the fish is abnormally dark in colour.
Angel (Scalare) color intense
Colours of Angel fish (Scalare) become more intensive.
Angel fish dip dorsal fin
Frequent dipping of dorsal fin by Angel fish (Scalare).
Abdomen sunken
The lower part of the fish's body is hollow and wasted.
Reluctant to feed
Fish comes to eat but with evident lack of appetite.


Several species of protozoan parasites, with eight flagella (Octomitus). Also called Hexamita and Spironucleus Typically infects Trout/Salmon, in aquaria Discus, Angels, Goldfish & Shubunkins. It is a Fresh and Marine water disease.

Life cycle believed to be direct, relative importance of trophozoites/cysts not known. Route of entry to GI tract may be by mouth &/ or rectum.


Disease that can be cured if recognized and treated. It was believed that the parasite caused secondary bacterial infections, that caused the so called "hole in the head" to appear.


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DNA and RNA diagnostic references

Spironucleus species: 
Economically-Important Fish Pathogens and Enigmatic Single-Celled Eukaryotes

From Journal of Aquaculture Research & Development Nov.2011.

Catrin F Williams, S.Poynton  et al.


Dr. Poynton, Sarah
Division of Comparitive Medicine
John Hopkins University of Medicine
Baltimore MD.  USA


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