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Pam Spindola

Tips for helping your fish through a stressful time -

The Koi Pond in Spring

by Pam Spindola, California USA
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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 temperature. 

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 through Aquatic 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 glass thermometer!
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.  

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