Five years ago I saw 3 cases. This
year I have seen 67. Hexamita is going to become a problem.
a small flagella around 3-6 micron in size and is a parasite found in the
intestinal tract of goldfish and koi. This was formerly a cichlid infection but
has been known about with carp and salmon and trout for a number of
Infected fish get extremely thin. The symptoms can take many
months to show if the infection is low and the fish were in good health when
infection was introduced .
Some times the abdomen can be distended
showing symptoms of dropsy. The intestines may contain a yellow mucoid
material. Recent taxonomic studies have labeled the intestinal flagellate with
other names such as spironucleus, hexamita, or sprironucleus.
diagnosed, make a squash preparation of the intestine, and examine under the
microscope at a magnification of 200-400, using phase contrast or semi close
your iris on your scope. Hexamita looks very similar to bacteria on a corpse.
The parasite can be found where the mucosa (intestine lining) is broken. They
move by spiralling and in heavy infections they will be too numerous to be
overlooked - like bacteria on a corpse.
In tropical fish, hexamita
mostly shows itself by holes developing around the head erea. In cichlids
including discus, symptoms sometimes show the signs you look for in koi - the
tadpole affect - all head and a thin body in it's latter stages, which also
fits the description of fish tuberculosis.
Notice the white marks on the top
of the fish's head and neck, like shallow craters, this form is far more common
when fish are kept in tanks rather than ponds.
In koi the marks are
very similar, but are smaller and more round and some times all around the
head. There is no set pattern and mostly appear in the latter stages of this
infection. They can also appear down the lateral line.
spreads faster in tanks than ponds. The problem is I would class a plant free
indoor heated pond 1000-2000 gals with high stock level as a tank, as infection
spreads as fast.
Notice that the fish look in good health and many do until
weight loss starts. Loosing weight may start before any holes appear, often
showing white string feaces sometimes transparent. In some cases the fish can
have this infection for many years with no ill affect to themselves while
affecting others - how and why I don't know
no need to mix with food. Example Case
advice from the Fish Helpline with regards to the diagnosis of hexamita, I
contacted my local vet to obtain the necessary medication-metronidazole. After
consultation, this was prescribed in tablet form 200mg per tablet. The ratio of
medication to food was calculated by the vet at 1-1/4 tablets to 100grams of
I weighed out 100 grams of dried pellets food and then crushed
this using a mortar and pestle to fine powder. I then crushed the 1/1/4 tablets
and mixed thoroughly with the crushed food. To bind the food back together so
that I could feed the fish I used gelatin, as advised by the vet. The gelatin
was obtained from local supermarket. I mixed the gelatin into hot water as per
instructions given on the packet using approximately half the sachet per 100gms
of fish food - this was a bit hit and miss until I found the correct
consistency to bind the food. The gelatin was added to the crushed food and
mixed thoroughly until all the liquid was absorbed, and the consistency was
like firm paste. This was then rolled by hand into large pellets approximately
15mm in diameter. These pellets were then cut using a sharp knife into smaller
segments (the size of normal food) 6mm. I found it easier to do this than try
to make small pellets initially.
The pellets were then allowed to set
for approximately 30mins or until cold. Tthe food was then fed individually to
The food should be fed at 1% of fishes body weight daily for
7 days to all fish, however this I found was very impractical. Please note that
once the food has been broken down and reconstituted with gelatin it does not
With kind permission from my client Mr. N I Rice.