Trichodina is protozoan ciliate parasite, which causes the condition commonly
known as sleeping sickness.
These parasites have been found in pond fish all year including winter. The parasite can reproduce
between temperatures of 4 degrees and 30 degrees C.
Reproduction is faster in dirty water than in clean water. Trichodina
are disc-shaped parasites and are easily identified under a microscope. They are around 70 microns in diameter, have typical
denticles or internal blades, and are covered in cilia, i.e. hair like extensions. They continually rotate and in this way
scrape small skin and gill particles from the fish with their denticles.
This causes countless small, irritating lesions,
on which the fish reacts with a heightened mucus production. This process brings about a white, greyish sheen on the fish.
The small lesions on the gills make it difficult for the fish to breath.
In a first stage, the fish will hang near the
bottom of the pond and shows extreme lethargy but will swim off erratically if disturbed. The fish does this in order to consume
only minimal amounts of oxygen.
In a more advanced stage the fish will breath for air at the surface. Some Trichodina
have proved to be harmless, but a serious infection can prove to be fatal, particularly in juvenile fish and after transportation
and in particular moving to different water as this causes stress and consequently reduces the fish immunity. Other conditions
of stress such as overpopulation and inferior water quality can increase the effects of the parasite.
The best treatment
for Trichodina is potassium permanganate (Condys Crystals). Because the parasite reproduces by binary fission, and does not
penetrate deep into the skin, it has been suggested that one treatment is sufficient. However it is my opinion that the parasite
is able to survive in the filters and when the pond is treated not all the parasites are eradicated, I would suggest that
three or four treatments over the period of one week will greatly increase the chances of eradicating the parasite. It is
important that the pond be aerated profusely during treatment. Other medications, which may prove useful, are chloramine-
T, formaldehyde and malachite green. A formalin / malachite green combination can be used although this may be more effective
against White Spot.
1) Chloramine T
This medication is a powerful disinfectant that is
effective against protozoan ectoparasites (such as trichodina and costia), fungi and bacterial infections. It can be used
to control secondary infections that may accompany a viral infection.
Chloramine T is used as a prolongued immersion and
may be repeated several times.
Dosage depends on the pH and the water hardness.
pH 6: 2.5g/10001 (soft water).
7g/10001 (hard water)
pH 6.5: 5g/10001 (soft water), 10g/10001 (hard water)
pH 7: 10g/10001 (soft water). 15g/10001
(hard water)
pH 7.5: 18g/10001 (soft water). 18g/10001 (hard water)
pH 8: 20g/10001 (soft water). 20g/10001 (hard
water)
As a consequence chloramine T is more toxic in soft water with a low pH
level. High doses may be toxic to both koi and humans. Avoid contact with human skin or eyes. Also do not combine with formalin.
Chloramine T should be stored in a dark and .cool place. Direct sunlight inactivates the product. It is important to aerate
sufficiently when using this product.
Chloramine T can also be used to disinfect materials but make sure the material
is rinsed and cleaned thoroughly to remove all residues.
2) FORMALIN
Formalin is an aqueous solution of 40% formaldehyde
gas. It is a toxic substance which causes skin and eye irritation in humans and as such should only be used outside or in
well ventilated areas. It should be stored in the dark. If a white precipitate forms in the bottle it cannot be used anymore.
Formalin is effective against most fungi and protozoan parasites such as costia.
The dosage for prolongued immersion
is 0.02 mI/litre. For a short bath it is 0.15 mI/litre for half an hour.
Like chloramine T, formalin is more toxic in
soft water with low pH and at higher temperatures under 8 degrees it loses its strength. Ponds must be aerated while using
formalin.
Doses above 0.025 mI/litre destroy nitrifying bacteria, when using a lower dose the filter does not have to
be turned off during treatment, only the uv light should be switched off, active carbon and Zeolite should also be removed
Formalin should not be mixed with potassium permanganate as this combination will cause severe skin and gill burns.
3) Malachite Green
This dark green powder can also be used to treat
parasites and fungi, it is also used to disinfect fish eggs. The activity of malachite green is highly temperature and pH
dependent, it is more active at higher temperatures and low pH. The dosage for prolongued treatment is 0.15mg/litre. For short
baths use 60mg/litre for 30 seconds, repeat twice a week. To treat eggs against fungi, use 10mg/litre of water for 15 minutes.
