Sharing Experience in the Breeding and Management of Japanese Koi

 I. Feeding Program

Japanese koi are omnivorous and, like people, have a good appetite for just about everything. Koi feed comes in two kinds, artificial and natural. Most koi enthusiasts mainly use artificial feed, and the feed composition varies depending on what it is being fed to. Fish meal mixed with malt is the main ingredient, as this is easier to digest. When the water temperature is lower, winter feed is used; color-enhancing feed contains carotenoids such as spirulina, while summer feed mainly promotes koi growth. In most cases, using these feeds in combination is already sufficient, but some koi enthusiasts add various other ingredients as well. Chinese cabbage and round cabbage are also foods koi love to eat. The number of feedings and the amount fed should vary with changes in water temperature and pond conditions. Broadly speaking, because koi have no stomach in which to store food, they should be fed small amounts many times.

II. Breeding Management

The actual breeding of Japanese koi should adapt to the changes of the seasons. In winter in Japan the water temperature is usually 5-10 degrees C. At this time of year, most Japanese koi are hibernating. When the water temperature drops below 5 degrees C, Japanese koi stop moving and stay at the bottom of the pond, and under such conditions no feeding is needed. When the water temperature is between 10 and 15 degrees C, they swim very slowly, and on warmer days they can be fed some starch-rich feed that is easy to digest, once every 2-3 days. Even if food is supplied every day, they will eat it, but avoid overfeeding. When the water temperature is lower, koi cannot fully digest the food they have taken in, which causes them to produce gelatinous feces and malfunction of their internal organs.

When the water temperature reaches 15-20 degrees C, koi become active. At this time they can be fed 1-2 times a day, with feed lower in protein and fat and easy to digest.

However, this season is also when many parasites multiply in large numbers, such as fish lice, anchor worms and the like. Once such parasites are found, they should be eliminated immediately.

When the water temperature reaches 20-25 degrees C, koi have the best appetite, and they also grow fastest at this time of year. The feed should be rich in protein and fat, and they can be fed 2-5 times a day. Color-enhancing foods should also be fed at this time. At present, this type of feed all has added to it carotenoid-rich phytoplankton, and the phytoplankton called spirulina is widely used in Japan. However, spirulina is not easy to digest, and only at this time of year can it be fed to koi. If the feed contains too much spirulina, it will cause koi skin to turn yellow and lead to malfunction of internal organs. It is recommended that the spirulina content in the feed should be between 10% and 15%. When the water temperature is above 30 degrees C, koi eat less, and the amount fed should be reduced accordingly.

When the water temperature gradually drops to 15-20 degrees C, both the amount and the number of feedings for koi should be reduced. This is also the time when koi are at their most beautiful in the year. Strengthening the feeding for skin color and considering nutrient absorption is better done during the warmer periods in autumn.

When the water temperature drops further to 15 degrees C, the amount fed should be greatly reduced, and below 10 degrees C feeding should stop.

The feeding process for each season is only an overall guiding framework; in actual practice, it should also be adjusted according to the condition of individual koi and the conditions of the breeding pond.