feeding your koi

Feeding your Koi a balanced, varied and nutritious diet is essential to their well being. I'm still shocked to meet some clients who have been told not to feed their fish by their pond installer. A few small fish in a very large pond may survive without feeding but their natural diet will still lack elements only a good staple food will provide

Feeding your fish is one of the highlights of the hobby. Their is nothing like seeing a school of koi rapidly converge in a rainbow of colour as they lunge for every pellet they can. Exciting as it is, it is also a prime opportunity to study your fish for health issues

If for example, if a fish fails to respond aggressively then there definitely is a problem. It is also an opportunity to have a glance at the undersides of your koi for ulcers - they will sit almost vertically in the water as they feed
  • You can tell this is quality food by the colour. This is Dainichi Premium Blend
  • Plankton is a high protein food that helps with reds
  • Tetra Koi Sticks are air filled making it deceivably expensive

When to feed your koi

Koi activity is based on temperature. If koi are active, they should be fed. If they are fed, filters should be operating. In Toronto this is typically from early/mid April until mid November

When water temperatures are above 10 Celsius [50 Fahrenheit] koi will want to feed. At these temps, a lower protein [wheat germ for example] food should be fed. This food is less expensive, easier to digest for the fish and does not pollute the water as readily

Once temperatures hit 15 Celsius [60 Fahrenheit] and above, more protein can be fed and fish will happily eat a couple of times a day. Above 19 C, several meals of a high quality protein food should be fed daily. At very high temperatures, 28 C and above, fish will likely slow down as oxygen levels are lower even at 100% saturation. This may be a problem in a shallow South Texas pond somewhere, but is atypical

Feed Fresh Food

It doesn't matter how good the food you are feeding is, if it is not fresh it will be lacking nutrients. Vitamin C can break down very quickly. Buy fresh food, store your food properly and throw out old food


There is an old saying - you are what you eat. The same rules apply with Koi foods. It is expensive to manufacture a quality food and therefore costly to invest in. But when consider the value, it is the only logical choice. Quality bagged foods start at about $10/lb. Besides keeping your fish healthy, there will be less waste in your filters when a better quality food is used


There is not one perfect meal we can eat day after day and remain healthy in the long term. Some vitamin or mineral will be lacking and this is the same when it comes to koi food. Do not feed your fish exclusively on one manufacturers feed. Mix it up and feed a variety of pellets from different companies. Throw in some fresh greens and fruits - which are fresh and not processed. Pineapple is purported to be a favorite food of koi although I have not tested this myself. Peas are great and very nutritious

Pellet Size

It is important to make sure that all your fish have a pellet size that they are comfortably able to swallow. However, I have always felt that medium sized pellets will be more readily absorbed than large pellets

Frequency and Duration

With water temperatures above 19 degrees, fish should be fed several times [up to 6] a day and the food should be gone within 5 minutes. I don't subscribe to a 10 minute feeding opportunity as koi have evolved as grazers. However I have seen 1 hobbyist let his fish eat for 20+ minutes and they were huge. At temperatures between 13 - 18 degrees, feeding 1-2 times per day is recommended. In extremely hot conditions, koi may stop feeding altogether

Seasonal Feeding Considerations

Lower protein foods should be fed with temperatures in the mid teens. These wheat germ based foods are easier to digest and do not produce as much ammonia. Protein levels in excess of 30% can be fed to accelerate growth during the peak Summer temperatures. It is important to aerate heavily during warm weather and with a heavy feeding regimen, more oxygen will be required

Do not feed your fish trout chow and other cheap foods. These contain too many oils and do not contain the right nutrients for koi. Inexpensive foods can also contribute to water quality and clarity issues and I have seen cases of twisted spines on fish who have been fed a poor diet

  • A feeding ring comes in handy for fish observation and to stop "feeding the skimmer"
  • Koi love duckweed, and it is a great source of protein and minerals

Koi Food Ingredient Analysis

Wheat Germ

A costly ingredient [as it makes up a small part of the plant] but an excellent carb and easy to digest - perfect for Fall and Spring feeding


An algae which provides high protein [approx. 50%]. It contains carotenoids which helps with developing better colour. Some of the better quality foods available have this as an ingredient


Corn Meal is found in many koi foods - it should not be a main ingredient and both it and wheat are usually used as a starch ingredient

Silk Worm Pupae

This insect provides high protein and was originally fed by Japanese Breeders. You can breed your own, there is a fair bit of work involved however but one of our clients did it


Loved by Koi and great for feeding to Tosai. These Krill, Shrimp, Plankton contain protein levels over 60%. Fed in warm water, they will promote growth and colour. While expensive, they are a worthwhile supplement. More expensive foods will have this ingredient in their pellets, or you can buy Krill/Shrimp/Plankton on its own for supplemental feeding. As fish love crustaceans, these are great for training your koi to hand feed

Montmorillonite Clay

This clay is very beneficial and can be added to the water as well as food. It contains numerous minerals and helps with digestion while increasing appetite. In pond water it also acts as a flocculent, clearing the water of minute particulate that is too light to settle out on its own

Vitamin C

Very important for your fish, it is probably best to offer them fresh citrus fruits rather than rely on a koi food to supply this vitamin. In koi foods look for stabilized vitamin C - Ascorbyl-2-Phosphate. This form is both absorbed well and is stable in the feed. Avoid the Ascorbyl-2-Sulfate form as it is not as digestible

mistakes made with feeding

Over Feeding

I often visit ponds to spot food floating on the surface around the sides - a sure sign of overfeeding. A more subtle sign of overfeeding can be floating feces. You are not only wasting food, but adding organics to the water which negatively impact the water quality. Food should be readily taken and eaten within 2-3 minutes in warmer temperatures. Avoid overfeeding - remember, healthy fish are always hungry

Under Feeding

Most ponds house too many fish to expect them to be able to find enough naturally occurring food to survive. Even in lightly stocked ponds, a good staple pellet should still be provided to balance the diet

Feeding Old Food

Try to buy from a dealer who has regular shipments of food coming in rather than one who stockpiles it. Food can spend an incredible amount of time in the manufacturing and distribution channels, particularly food from over seas. All the while its nutrient content is diminishing

Buying Low Quality Food

Like a lot things, the initial low cost could come back to haunt you down the road. Poor foods don't digest as well and increase the loads on your filters and they will require more frequent cleaning. Additionally they can ruin a koi's conformation and fail to provide the nutritional building blocks for fish to grow well and stay healthy. At the end of the day, purchase a quality food with good nutrients so that your fish have every opportunity to thrive