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There are many issues that can cause concern to our fish, this article, whilst by no means definative, aims to give you an indication of the main areas of concern to keep an eye on.
Water Quality
Any differing water parameters can have a major impact on the well being of our Koi.
Generally, in Japan, the water is quite soft with a pH around 6.0 to
7.0. We then introduce them to generally hard water with a pH of around
8.0 or more. i.e., at least 10 time more alkaline than they have been used
to all their lives. This on its own produces a major shock to the koi’s
system
and coupled with the stress created by the journey from Japan as mentioned
above, it is quite remarkable that these new imports survive the
first week in their new environment at all!
Quarantine Regimes
So what I here you say, this has been happening for years, why in some years
do we seem to get more health problems than others? Well read on
‘cause there are a number of other factors which may not be so
obvious – like our quarantine regime!
We seem obsessed with the idea
that the new Koi imports are riddled with parasites and bacterial
disease and that we need to wear breathing apparatus and surgical
gloves to go near them!
Some Koi dealers still feel obliged to
dump their new imports into some frothing cocktail of medications
when the new fish arrive just in case they are carrying something
nasty.
So we treat our newly arrived fish, stressed up to the
nines from their journey, to a nice bath of Potassium or
Chloramine or Malachite – just in case! Nice one!!!
Koi need excellent water
quality and little else after being subjected to their journey and
the stresses induced. After they have begun to settle in for a
week or so then is the time to consider appropriate treatments –
but only if required. If the Koi are free of parasites, we don’t need to
treat for them at all.
Genetic Weakness
The fact is
that our Koi are produced by selective inbreeding with parent fish
being mated with offspring from previous spawning in order to
improve colour and pattern. It is my belief that for every year
that goes past, and the pattern of inbreeding continues, our Koi
are becoming progressively genetically weaker and this renders
them far more susceptible to disease (as for any pedigree animal).
Fortunately, breeders do replace breeding stock from time to time,
either because they are forced to as a result of the death of one
of the parent stocks, or more frequently because they need to
improve a particular trait of the offspring produced, e.g. size,
pattern, colour etc.
Also, it is pleasing to note
that some breeders are now introducing fresh bloodlines into their
broodstock with the specific intent of improving the strength of
the bloodline. A super example of this is Sakai in Isawa. (Matsunosuke),
who has in recent years been introducing Magoi back into his
breeding stock in order to improve both the size of offspring but
also the strength. He has been doing this for the last few years
and I have to say that the result, which I have experienced, is
that his fish have been relatively free of disease problems over
the last three years or so.
If you are unfortunate enough
to experience a disease problem with your Koi collection, it will
almost certainly be the most highly inbred varieties that suffer
first, with Go Sanke and Utsuri varieties most at risk, and Asagi
and Chagoi least vulnerable as they are closer to the original Koi
and are subsequently much stronger genetically.
Breeders husbandry. We have to
remember that Koi farms are commercial entities and are concerned
to get their product to market in peak condition. They are
however; less concerned with what happens after the fish leaves
their premises i.e., they are not so concerned with the
long-term health of their stock. Their treatment and husbandry are
directed at short-term benefit.
Misuse of Antibiotics
This is a most worrying problem of
them all. Not to be confused with
the prophylactic treatment using antibiotic, but with the
legitimate use of antibiotic to treat identified problems.
It started with oxylinic acid, the first antibiotic to be used and
abused so much in Japan that it is now just about useless. Why?
‘cause the bugs have mutated and become immune to the drug'. This
is happening more and more, and for the first time last year, we
saw evidence that the same thing is happening to Baytril, up till
now one of the main weapons in the fight against bacterial
disease. Once the breeder has discovered a drug that works – he
uses it en mass and bugger the consequences!
Now we are finding that Baytril and indeed other important drugs
are far less effective against common bacteria.
This is one reason why people
have been jumping on the bandwagon and saying that there are new,
resistant super bugs and viruses appearing in Koi imports.
The truth is that it is the same old aeromonas that are causing
the problems because they are becoming resistant to our everyday drugs.
Maybe they are super bugs, but if they are then WE HAVE MADE THEM THAT
WAY. Yes, it’s not just the good old Japanese breeder who are to
blame, for we have to take our share of the blame as well.
As any doctor will tell you, if
you are prescribed a course of antibiotics, you must finish the
course and not stop taking the drug when you feel better. The reason
is that you must kill all the bacteria. Any left that survive can
develop a resistance to the drug used and then breed and pass this
resistance on. Koi given antibiotic should be injected with a course
of three or four injections to ensure that the drug has the desired
effect. One injection is not enough, and there is a very real risk
that Koi treated in this way will pass on resistant bacteria to
their fellow pond inmates, even if they themselves get better.
Quarantine Again
A period of quarantine is vital
to catch any potential problems and keep them isolated with the
new stocks. Ignore this simple rule at your peril. A number of
hobbyists last year ignored this rule (not just me) but apparently
imported the virus mentioned above with the result that they wiped
out their entire collections. It can and does happen – so be
warned!
Disease Resistance
Another theory about this, and that is
all it is, but evidence has suggested now and on several occasions that
fish newly introduced into an established collection i.e. not just
newly imported fish, can introduce ‘new’ bacteria into the
existing stocks and whilst this can cause health problems with the
existing collection, the newly introduced stocks are appear to
remain unaffected. This also can happen in reverse and the newly
introduced stocks can be susceptible to disease by being
introduced to ‘old’ bugs currently in the environment, which
apparently have no detrimental affect on the existing stocks.
Over the last year or so however, we
have also again seen a very large number of existing Koi collections
that have been affected by all kinds of disease problems, and many
of these have not introduced any new fish at all. How many times have we
heard ‘my fish have been fine for years, but suddenly this year I
have suffered losses’?
So if it is not new fish bringing
in problems, what are the causes of disease. Well there are the same
reasons that there have always been, and some of these may not be as
obvious as first thought.-
Poor Water Quality
We get complacent, don’t both to check our water parameters weekly,
forget the weekly water change and keep chucking in mountains of
food……Until eventually our koi are showing signs of
ulceration, or parasites and when we check our water we find that
ammonia and nitrite levels are too high.
Make no mistake, low levels of
nitrite and ammonia which are permanent will stress your koi.
Stress can lead to either parasite infestation or bacterial
disease or both.
We must bear in mind that our
koi are living in an artificial, closed environment; a bacterial
soup if you like and we need to be vigilant to ensure premium
quality water conditions at all times.
Overstocking. Still one of the
biggest killers of koi. Leads to poor water quality as above and
an increased chance of cross infection. Once one fish develops a
problem, it’s neighbour's can quickly succumb. The general rule
of thumb is one fish inch to every 10 gallons. I know most of us
don’t stick to this rule but it is a fact that the higher the
stocking rate, the greater is chance of a disease outbreak
occurring
Inappropriate Treatments
Your fish are jumping; it’s spring so your fish must be suffering
from parasites. Chuck in some Malachite and Formalin just in case.
Result – fish that were probably very happy and full of the joys
of spring and free of parasites are now stressed after a week or
so living in chemicals that they didn’t need. Obviously the pond
may need medicating from time to time, but ensure that you
investigate the cause of any perceived problem and apply the
correct treatment
Cleaning out the Filter
Some hobbyists still believe they should be cleaning out their filter
every week and switching off their pumps altogether in winter. I
am amazed at just how often I have come across disease problems
apparently caused by these factors. If you need to clean your
filter out every week, it’s the wrong filter and you need to do
something about it! A mature filter should not need cleaning more
than once per year and then only one chamber at a time
Poisons
Not as uncommon as it
may sound, with inappropriate wood preservatives, poor fibre
glassing and use of dangerous substances, such as polystyrene
coming into contact with the water, closely followed by
inadvertent dosing with weed killers or slug pellets. I know of a
least one very toxic weed killer which is guaranteed to kill patio
weeds for up to 3 years with just one treatment which is currently
being offered in the koi market as a pond additive to kill blanket
weed. And we wonder why we get problems!!
There are of course a myriad of
other reasons that could potentially lead to a disease problem but
most of these result in poor water quality which is the ultimate
culprit in the vast majority of cases. |
