Bacteria
Bacterial Infections
Bacterial Infections: (The following is meant to be a very simple explanation
of why bacterial infections occur and how to treat them. For a more detailed
discussion see "Koi Health and Disease" by Dr. Erik L. Johnson, D.V.M.)
The two most common bacteria that cause problems on koi fish are Aeromonas
and Pseudomonas. Both of these bacteria are naturally occurring and are
found in all pond and lake water. These bacteria are non existent in tap
water because chlorine is added to kill any bacteria. Never the less, you
can start up a brand new pond with tap water and within 3 weeks after the
chlorine has evaporated, you will find at least a low level of these bacteria
in your water. Normally, in a clean healthy pond, the levels of bacteria
are so low that they will not cause a problem on their own. The outer slime
coat or epidermis normally protects the fish from these harmful bacteria.
The most common reason koi
experience a bacterial infection is when their slime coat or epidermal
layer is broken and the bacteria is allowed to infect the koi. These sores
can grow very quickly if they are not treated. See photos Here
The most common reasons infections start
Parasites can
eat through the outer slime coat or epidermal layer exposing the dermis
layer to the bacteria. As flukes attach themselves to the surface of the
koi with their haptens, which resemble small fish hooks, they can actually
inject the harmful bacteria into the koi.
Scratching against
a sharp object such as a rock can break through the slime coat and expose
the koi to the bacteria.
Poor water quality can
burn off the slime coat or stress the koi making it more susceptible to
the bacteria.
Stress by itself
through overcrowding or simply moving fish from one pond to another can
sometimes be enough to allow a
bacterial infection to start.
Treatment for Bacterial Infection
Treatment can be handled in several ways depending
on the severity of the infection.
On small sores you can dry off the wound with a paper towel and then
treat the wound with hydrogen peroxide on a q-tip. Let it soak for about
30 seconds before placing the koi back into the water. Repeat this procedure
3 days in a row. On larger sores after treating with hydrogen peroxide,
again dry off the wound and apply Debride Medicated Ointment to the sore.
Repeat this procedure 3 days in a row.
Potassium Permanganate mixed with water to make a light paste can be
very successful in treating wounds. You can substitute the hydrogen peroxide
in steps 1 and 2 above with this paste. The only disadvantage to using
the paste is that the wound will be stained a dark purple for a couple
of days which makes it harder to tell if the wound is healing. Aside from
that it is a very effective treatment. Do not use on a wound that is already
healing because it will destroy the fragile new cells. Sometimes medicated
food can be effective, especially if you have a hard time catching the
fish or the fish are too small to inject. The problem with medicated food
is that often times the fish that need the medication the most are too
sick to eat it.
By far the most effective way to treat a bacterial
infection is to inject the koi with antibiotics.
This gets the proper amount of medication directly into the koi. The easiest
way to inject a koi is to guide the koi into a clear plastic bread bag,
drain out the excess water, roll the koi over on its back, pull the excess
bag back until the bag is tight around the koi and then inject the koi
through the bag in the area between the anus and the ventral fins at a
slight angle toward the head. The koi should be given an injection once
a day for three days in a row and then every other day for two more injections.
If the water is below 55 degrees spread out the injections to one every
other day for a total of 5 injections. This is necessary because the koi's
metabolism is very slow below 55 degrees. To inject the koi, use a 1cc
diabetic syringe with a 25 gauge, ¾ inch needle. You will need to get
the antibiotics through your local veterinarian. For photos illustrating
injections click Here
Heat is very important in the healing process. During the summer months
when the water is warm, bacterial infections will grow very fast, but they
will also heal very fast fast once properly treated. During the winter
time when the water is below 58 degrees koi fish wounds take a very long
time to heal. If you have the ability to slowly warm up (5 degrees per
day) the water the koi are in, to 76 degrees, it is impressive how quickly
they can heal. Salt added to the water of koi with bacterial infections
can be beneficial. If the infection has created a hole in the outer skin
of the koi, water will begin to enter the koi through osmosis because the
fluid in the koi is slightly salty. By raising the salt in the water to
around .3% it will stop this proccess and spare the koi's kidneys the stress
of trying to remove all this extra water. It is important to try and establish
why the koi has a bacterial infection to begin with. If it is a secondary
infection caused by
some initial trauma (whether it is parasites, water quality or the
stress of overcrowding) unless the initial reason for the infection is
corrected you will not be able to successfully treat the infection.
