The Koi Pond in Spring
by Pam Spindola, California USA
Click images to enlarge
Flowers are starting to bud and cherry blossoms are coming into
bloom. The birds are more melodious and busy feeding their young.
The promise of spring and warmer days ahead is in the air. As
we observe the koi pond, we notice our fish are no longer little
submarines clustered at the bottom of the pond. They are at the
surface, exercising around the pond, and begging for food unashamedly
every time someone walks by.
This season is perhaps the most critical time for maintaining
a healthy pond. Not only do the warmer months signal more activity
for the koi, it is a time when the koi are more susceptible to
disease-causing organisms. Below 47° F (8° C), the immune
system of a koi is not fully functional. As the temperature rises,
there is a span of opportunity called "Aeromonas Alley"
when the pathogens in the pond environment are more active than
the koi's immune system. Aeromonas is a strain of bacteria that
can cause infections in koi weakened by stress or poor water
conditions. Fish do not like changes in their environment, including
This is a stressful time for a koi. In order to lessen the
trauma of the change in temperature and environment and the susceptibility
to disease, the hobbyist must protect the koi by committing to
a routine of maintenance of the filters, careful testing of water
quality, have vigilance for koi health, and supply proper nutrition.
All of these activities will pay off for a healthy pond and healthy
koi during the spring, summer and fall months.
Our koi greet us at the edge of the pond, their mouths open.
They have not been fed all winter when the temperatures hovered
at 50° F (10° C) or lower. By the way, even in sunny
California, I stopped feeding my pond during the colder months.
It was difficult for me not to feel guilt as my pond is at the
front entrance to my home and they greeted me daily, ever hopeful
for a few morsels.
The metabolic rate of koi is influenced partly by outside temperatures.
Below 55° F (12°C) koi actually stop producing antibodies
and at 45° F (7° C) enter a state of hibernation. As
the temperature warms, the koi have an increasing appetite and
their digestive system becomes active. To begin their diet I
feed the koi cooked oatmeal, cooked rice, citrus such as halved
lemons and oranges. In addition, fresh spinach and lettuce leaves
or frozen peas are always appreciated by my koi. I feed sparingly
at first, maybe every other day. It is said that at this time,
the koi only need a small quantity of food. We always think they
must be starving but their systems have been in hibernation.
As the temperature increases, it is suggested to add wheat germ
pellets which are easily digested. Currently I am feeding wheat
germ pellets only once a day in the morning. I continue to supplement
with citrus and greens. I have thrown out costly koi food left
over from the previous year. It may have lost its nutritional
value as the fish oils, one of the main ingredients, have a tendency
to go rancid and the amino acids and vitamins degenerate. I did
not want to jeopardize the health of my fish.
According to the Koi Health Advisory program of Associated
Koi Clubs of America here are feeding guidelines:
Less than 50° F do not feed
50° F - 60° F (10° - 15° C) -- 2-4 times weekly
60° F - 85° F (15° - 29° C) -- 2-4 times daily
Above 85° F (29° C) -- do not feed.
By the way, there is an inexpensive water thermometer available
Eco-Systems that has a small digital read-out of the water
temperature and a 30" cable-connected submersible probe.
It uses 1 AAA battery. Now it is so easy to track the water temperature
of the pond daily without having to read through a green murky
It is important to have good water quality. Make sure all the
detritus is out of the pond. Clean the biological filters. If
necessary, seed the filter with freeze-dried or live culture
bacteria to stimulate the production of nitrifying bacteria.
Test the water for ammonia, nitrites, nitrates, pH. If the nitrite
levels are high (a normal reading should be zero) this is a sign
that the bio-converter or biological filter is not working optimally.
This pond needs cleaning.
Nitrite is produced by autotrophic bacteria combining with
oxygen and ammonia. When the sudden increase in the bio-converter
load is greater than the bacterial action in the bio-converter
then the nitrite levels will rise. It has been named the invisible
killer since nitrites cannot be seen but they can be deadly,
especially to smaller koi. Long term lower concentrations of
nitrite on larger koi can damage the gills, curling them outward
and can damage the internal organs.
To alleviate this situation small water changes are helpful.
If the nitrite level is less than 1 ppm a 10% water change is
recommended. It is also recommended to add salt at the rate of
1 pound (.45 kilogram) per 100 gallons (378 liters) of pond water.
Between 1 and 2 ppm, change 25% of the volume of water and add
2 pounds (.9 kilograms) of salt per 100 gallons (378 liters)
of pond water. Greater than 2 ppm, change 50% of the water and
add 3 pounds (1.3 kilograms) of salt per 100 gallons (378 liters)
of pond water. Salt helps to reduce the toxicity of nitrites.
Remember not to add salt if you have water plants in the pond.
Also, increase the aeration of the water by adding air stones.
As the weather improves, we spend more time outdoors and tend
to enjoy the pond more. Maintain constant observation of the
koi and watch for beginning signs of fungal, parasitic, or bacterial
infections. It is so much easier to treat at the beginning of
a problem then when it gets out of hand.
Have patience as the biological filters return to full activity.
Lastly, feed the koi easily digestible foods in small portions.
With the help of a regimented and vigilant koikeeper, the koi
will weather the hazards of spring.
WGI ONLINE Journal
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