Page 47 - Koi Net - On-Line Koi Magazine - Issue 78

SPRING PARASITE

PROBLEMS

Bernice Brewster Bsc, FLS, MIFM,
CBiol, MIBiol

As Koi are cold-blooded, their body temperature is
only slightly higher then the surrounding water, although
breathing and muscle movement keeps their
temperature very slightly above the environment. It
seems to have been a long winter, with a mild but wet
start and in recent weeks warm days and freezing
PARASITES overnight temperatures, which means the water starts
WHICH TEND to warm up in the daytime but cools again overnight.
Because the immune system of the Koi is less effective
TO BE ACTIVE during the winter months, these fluctuating

IN THE temperatures plus a sluggish immunity, can lead to
outbreaks of parasite infections. The most obvious
SPRING ARE signs of parasite infections are repeatedly flashing and
MICROSCOPIC rubbing on the pond surfaces, occasionally jumping or
clamped fins. Before breaking out a microscope, it is a
ONES good idea to just check the water quality and ensure it
is free of ammonia and nitrite, especially nitrite which is
a skin irritant and may also cause the Koi to display the
same sign as a parasite infection.

The parasites which tend to be active in the spring are
microscopic ones, invisible to the naked eye and require
a mucus scrape to be taken from the Koi. Before netting
and sampling the mucus, it’s worth taking a few minutes
to check over the microscope, gently clean any dust
from the eye pieces and light source and check it is set
up correctly.
Trichodina
Whilst a nuisance, Trichodina is not a true parasite of
fish, it is mostly free-living and found in the filters and
pipework of the pond, where it feeds on bacteria and
pieces of organic material. In side view, Trichodina is

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