There has been a lot of discussion about koi food – how much to feed, how often to feed and what type to feed. A lot of time and energy is spent creating an artificial environment for Japanese koi. Some may try to create a natural environment in a koi watergarden with plants and even a gravel bottom. The koi watergarden uses both mechanical and biological filtration as well as plants to keep the water quality high. A koi only pond relies totally on mechanical and biological filtration to keep the water quality high. So what does koi food have to do with water quality? Why feed an easy to digest food in cooler water temperatures and high protein in the summer months? Why is it best not to feed koi when the water temperature is below 50°F? To answer these questions we have to consider the natural environment of koi and where they originated.

Japanese Koi Natural Environment
Koi are basically colored carp that originated from mutated carp in the Niigata prefecture in Japan. This is a mountainous region that receives substantial snow fall in the winter months. In Niigata the carp were originally raised in earthen ponds as a food source until mutated colors were discovered in the early 1800s. Selective breeding has given way to the colorful varieties we have today. Koi are omnivorous, meaning that they eat vegetable and meat matter in the form of aquatic plants, algae, crustaceans, worms, larvae and silt. The protein content in their natural environment is much higher than the koi foods that we provide today. The whiskers on koi, like catfish, are like taste buds that help them forage for foods on the bottom. Since koi do not have stomachs, whatever they eat is not stored but instead digested for the purpose of growth, color and energy. Whatever is not utilized is excreted as waste. Japanese koi are cold blooded and their metabolism is dependant on the water temperature. This metabolism peaks at just over 70°F when most of their growth takes place. At this time most of the proteins are utilized for growth and there is little waste excreted. When the water temperature falls below 70°F they are not using the proteins for growth and there is more waste excreted in the form of ammonia. This matters little in their natural environment where population densities are much less than in a modern koi pond or koi watergarden.

The Metabolism of a Koi Pond or Koi Watergarden

Just as the metabolism of koi is dependant on water temperature, so is the metabolism of the koi pond or koi watergarden. They both tend to peak and go into a dormant state at the same time. In the winter months every thing seems to come to a stand still including biological activity. It is the biological activity of denitrifying bacteria that keeps the water quality high. Plants that would utilize and remove waste are also at a dormant state. Even though the mechanical filtration is doing its job of removing debris before it has a chance to break down, there is little if anything to deal with ammonia or nitrates that can build up. This is especially true in the transition months in the spring and fall. In the fall season plants are dying back and leaves are blowing into the pond as mechanical filters struggle to keep up. Feeding a high protein food at this time could very easily cause water quality that was in balance to degrade to an ammonia soup in a very short time. Likewise in the spring when the water temperature is below 70°F feeding a high protein diet would wreak havoc on water quality. Leaves and other debris that were not caught by mechanical filtration are starting to break down as the water temperature warms. Denitrifying bacteria lags behind in the metabolism peak which is why there is often an algae outbreak in the spring that tends to go away when water temperatures go up to over 70°F.

Different Koi Food For Different Seasons

High quality koi foods that are available today are formulated to the needs of koi in an artificial environment. In a totally natural koi pond we would not have to feed our koi at all. However, in this environment the waters would be turbid and enjoying the beauty of the koi greatly diminished. Having crystal clear water allows us to enjoy and interact with the beauty of these fish. It is imperative to feed a high quality koi food that is correct for the season and water temperature. A high quality all season koi food should be high in vegetable matter, lower in protein and easy to digest. It should also include vital nutrients and minerals that koi need for color and health. This will create less waste to foul the water in the cooler months. The best koi foods meeting this criteria are Dainichi All-Season and Saki-Hikari Multiseason. A high quality summer food should contain at least 40% protein to provide for high growth. It should also have nutrients and minerals for good color and health. The best koi foods in this category are Dainichi Growth and Saki-Hikari Growth. The recommendations are as follows. Never feed koi when the water temperature is below 50°F. From 50°F – 60°F feed an all season koi food 2-3 times a week. From 60°F – 70°F feed an all season food 1 – 2 times a day. From 70°F – 85°F feed a summer koi food 3 – 5 times a day. Slow the feeding when water temperature rises above 85°F to 1 – 2 times per day. Koi tend to lose their appetite when the water gets this warm. During the fall, when the water temperature starts to fall and the daylight hours are less, koi stop growing. This is also the time when their colors become richer. Many koi keepers at this time supplement the koi diet with a color intensifier. Koi naturally put on color at this time and it is important to provide a koi food with sufficient nutrients to help this process. The main ingredients in koi food for color enhancement is spirulina algae and krill. Dainichi Premium has color enhancers along with proteins for high growth. The Dainichi color Intensifier is loaded with krill and spirulina. Saki-Hikari Color Enhancer is loaded with Spirulina. Both Dainichi and Hikari koi foods have many years of research and development built into their koi food formulas. They also have a proven track record of creating champion koi. Feeding a high quality koi food may seem a little pricey, but the benefits far out weigh the cost, resulting in better growth and color with fewer outbreaks of disease and mortalities.