Even one parasite warrants immediate action
The parasite Chilodonella is a major threat to fish health and
finding even one parasite warrants immediate treatment. Chilodonella
is a potentially dangerous parasite for two reasons. First, unlike
many parasites, it has a wide range of temperature tolerance and
outbreaks often occur at low temperatures when fish are least able to
resist. Secondly, despite is relative small size it, is potentially more
dangerous than Ich, because in the initial stages there are no readily
visible signs of its presence.
click on pictures to enlarge them
Chilodonella at 400x magnification
Chilodonella as seen in a wet mount of
a skin scrape
Often by the time it becomes obvious that something is wrong there
may already be severe tissue damage. As with other parasites there is
also the risk of secondary infections resulting from lesions caused by
the parasite's feeding activity.
The clinical signs are the same as all other parasite infestations.
Heavy and laboured 'breathing' (judged by watching operculum
movements), flashing and rubbing, skin cloudiness caused by excess
mucus, loss of appetite and lethargy. At a later advanced stage
(which may be too late for treatment) fish often isolate
themselves, sometimes near the water surface or water return. They
can also exhibit extreme lethargy with long spells laying on the bottom
with clamped fins.
It can be easily recognized in skin scrapes and gill biopsies from
its characteristic slow gliding movements, often turning in circles.
It has a flattened shape, heart-shaped with a notched end. There are
bands of cilia on the ventral (bottom) surface, just faintly visible in
the photomicrograph. They measure around 30 - 80 Ám in length x 20 -60
Ám width. - slightly smaller than skin-dwelling Trichodina.
Chilodonella is usually easy to treat with any proprietary parasite treatment, malachite and formalin, potassium permanganate, copper or salt baths. One treatment is usually sufficient