Koi should grow an average of one inch per month, provided they are fed an adequate amount of food. The amount of food recommended is what they can consume in 5 minutes. In summer, feed at least 3 times a day with a high protein pellet diet, incorporating some fresh fruit (they love oranges and watermelon). You can supplement with dried shrimp or color enhancing food to bring out their color. But be aware that some black and white koi may develop red spots. Koi food that contains spirulina can make their colors more vivid.
Signs of Underfeeding
- Poor Color
- Heads wider than bodies
- Slightly sunken eyes
- Kink at base of tail
- White stools
Temperature has a lot of influence on feeding. Be aware that when koi are fed in water temperature below 65°F, the filtration bacteria will be less effective, and Ammonia and Nitrite levels could spike. Test the water to ensure your pond is balanced. In cooler water temperatures of 55°F-60°F, feeding once a day is sufficient. Feeding is not recommended when water temperature reaches 50°F or below.
Overfeeding in warmer water temperatures above 80°F can cause your water to become cloudy and will reduce the oxygen levels. If you are overfeeding and your filtration system cannot handle the waste produced by the koi, you will have too many toxins in the water, so water changes are recommended more than once a day.
Overfeeding can also cause problems. Koi that are overfed will have huge hanging bellies, appearing like tadpoles with big body and wispy tail. In time, overfeeding will harm their liver and internal organs as they will not be able to process the food fast enough. This is all dependent on pond size and number of fish. Koi should be fed at least three times a day when the water temperature allows it.