SAY HELLO AND GOOD BYE TO THE GILL FLUKES
By Jim E. Quarles
These creatures are the number one problem encountered when keeping
discus and angelfish. I can safely state that sooner or later, and
generally sooner anyone who keeps discus fish will be the unwelcome host
to these killers. Let me state something at the outset of this article.
These parasites love a dirty tank, with the inside of the glass coated
with fish slime that is not wiped off when water changes are made. It
gives them a perfect place to hang on or deposit eggs to hatch and climb
aboard your fish as they swim by.
SO WHY DO FLUKES CAUSE SO MUCH TROUBLE
WHEN PREVENTION AND CURE IS SO EASY?
The answer to that question begs other questions, like how do you know
if your fish are suffering from gill flukes? And also few realize what a
problem it is until they start losing fish or the fish become so weak that
other diseases manifest themselves and mask the gill infections. Knowing
when you have the parasites on your fish it is much easier if you have
even a low power microscope or even a hand held lens that allows you to
take a close look at the gills or scrapings from them. If you don't have a
microscope, you must rely on your naked eye to tell you if the fish
signs of gill flukes. This is the hard way to become aware of the problem,
but there are reliable signs that can tip you off to the onset of the
parasitic infestation. Upon close examination you will note a
discoloration of the gills, they will become pink, they should always be
bright red. Off colored gill filaments are a sign of disease. Dactylogyrus
spp, on gill filaments Photo credit to Tetra Press
In the past an enormous range of chemicals were used to treat external
Parasites. But one draw back must always be kept in mind when applying any
treatment. Certain chemicals will reduce or kill your filter bed or
system. Treatment is a trade off when damaging chemicals are employed.
Below are named a few of many chemicals or compounds that have been used,
I will not note the dosages except in one case, if you elect to use any
treatment full dosages should be clearly understood and their expected
effects before treatment is started.
Formalin, formaldehyde, gas in water. Be careful, this is nasty stuff.
Malachite Green, this is a dye that is active against a wide range of
external parasites. It must be zinc free. Malachite green with Formalin.
Again, be careful, this is a dangerous chemical. Another chemical commonly
used is copper, but some fish are super sensitive to copper and testing
must be done to make sure only the proper dosage is applied over time to
the water. Fairly recently a new drug has become available to the discus
hobbyist to help control gill flukes and other types of parasites.
Praziquantel, currently sold under the trade name Droncit among other
names, will quickly rid you of these parasites, and it appears to have
little or no effect on the bio-filters in use at the same time. Discus, by
test can withstand fairly heavy doses of Praququantel with no lasting or
harmful affects. I recommend 3 to 4 ppm mixed in water for a first
treatment, and this should be repeated on a regular bases and become part
of your discus house keeping.
Oh yes, one final note. Praququantel or droncit, is not F.D.A. approved
for the treatment of fish. However like a lot of other under the counter
drugs you will find little problem obtaining it.