Spring is the time when the koi awakes from a long hibernation. The koi which has eaten a little feed during the winter is not in a good state to eat feed so soon.

At around 12｡C of water temperature. digestible feed such as boiled wheat or "Embryo buds-containing Feed" of our own developing, which is rich in protein. and of high digestibility and absorptivity, is given to the koi little by little.

Once a day is an appropriate feeding frequency. Even if the koi wants more, you may as well not give any more feed. This is the best way to save the life of the koi, and that amount of feed is good enough to the koi. When water temperature rises to 18｡C, feeding of three times a day doesn't matter.

Spring is the season when not only the koi starts to move actively but bacteria and parasites propagate because of the rise of water temperature. It is the time when the koi catches diseases easily, so make sure of the health of the koi every day. If necessary, disirlfect the pond and clean the filter tank.

20｡C and above is the optimum water temperature for the keeping. You can give the koi protein-rich feed as much as the koi can eat. Here is one thing that you have to be careful. In summer the koi begins to show a good appetite. and at the same time, there is a risk of the oxygen supply shrinking. Therefore, do aeration to the extent that it is too much.

Summer is the season when phytoplankton (Aoko) propagate themselves rapidly and the water turns green easily. You have to control the rapid propagation of Aoko by setting up an ultraviolet sterilization lamp.

The very strong sunlight is not good to the koi. Protect the koi from the ultraviolet ray by shadowing at least two thirds of the pond. During this season, the pond and the filter tank get dirty easily. If you neglect your duty, it is not long before the environment of them is deteriorated. Therefore, make a careful checkup of the filter tank and clean it. Do the checkup by chemical reagents to find out the value of pH. the concentration of nitrous acid. and the value of dissolve oxygen (DO) .

With the approach of autumn, the koi come to show a good appetite. At the same time, it grows in flesh and gains color. A sufficient supply of feed during the autunm, that is to say, the feeding of three to four times a day, will enable the koi to reserve energy for the coming winter. However, be careful not to give too much feed, but as much as feed the koi can eat per meal. With the decline of water temperature, decrease the feeding amount and frequency gradually.

From October through November is the time of harvesting throughout Japan. This is the final stage of all the work to make an excellent koi. That is, a promising koi (Tategoi) is released into a natural pond early in spring, then it is taken care of there over the summer, and finally it is harvested in autumn. The koi raised in the natural environment for six months will surprisingly look stout and beautiful owing to natural feed and enough exercise.

When winter comes. the koi comes to stay still at the bottom of the pond. The time has finally come for the koi to hibernate. Make a gradual decrease of feed for the preparation. When the thermometer stands at 10｡C or below, switch to the feed for a low water temperature. Give a limited amount of feed once or twice a week on a fine day. The supply of a small amount of feed during the winter doesnlt stop the movement of the digestive organs of the koi. This helps make the resumption of feeding smooth early in spring.

In the area where water temperature becomes 8｡C and below, a heating device is necessary. After the pond has been covered with something, a heating system (a boiler or a warmer) is equipped or warm underground water is poured into the pond. Winter is the season when water temperature is low and the koi declines in strength. Careful attention should be paid to the koi for fear of being attacked by diseases.