Koi and Goldfish Nutrition



Without proper nutrition you can not have good health. Therefore, we put together this page as a piece of the Koi and Goldfish Health puzzle. Topics include:

Koi and Goldfish Health is also highly dependent on disease management, water quality and environmental conditions. Therefore, we have put together a page covering each of these issues. Visit them at the following links:


Nutritional Requirements

Koi and Goldfish are omnivorous, which basically means that they will eat anything they can fit in their mouths. When in the wild or in more natural ponds with lots of algae and mud bottoms, these fish will do very well on their own and require little to no supplemental feeds. However, once they are put in an artificial setting which is filtered to be kept clean and dosed with algaecides to keep the algae at a minimum, many of the natural foods are removed and they become dependent on their keepers for nutrition. In general, it is a good idea to feed Koi and Goldfish a variety of foods to be sure that all required nutrients are accounted for. Most quality feeds on the market are more or less complete and the fish will do well on them, but an important vitamin or mineral may be limited. Therefore, if you feed multiple diets you stand a better chance of covering all the requirements. This can be done by mixing pellets together or feeding two foods on alternate days. However, for the fish to excel, they should have a variety of foods, including some natural feed.

Staple Diets

You can think of a Koi or Goldfish Staple diet as their everyday diet. This is a well balanced affordable diet that will keep your fish healthy and allow them to grow. It should have a protein level of 30 to 35% with one of the top 3 ingredients being fishmeal, shrimp or krill. We offer Keystone Koi Pellets as the everyday diet that we raise our Koi with. It is an exceptional value with a balance that allows it to be fed year round at water temperatures down to 50F. This feed also includes the color enhancing pigment Spirulina, which makes it the most complete feed that we offer. Tetra Pond Sticks and Blackwater Color Diet are other good every day Staple diets that we offer.

Wheat Germ Diets

Wheat Germ Diets are fed to Koi and Goldfish, particularly when water temperatures drop into the 50 to 68F range, because they are more easily assimilated than animal proteins. They are also fed sometimes during particularly stressful periods, such as handling and before and after disease treatments. Keystone Koi Pellets, the most versatile pellets that we sell, are also considered a Wheat Germ Diet and fish do very well with this in cool conditions. Other cool season feeds that we offer include Hikari Wheat-Germ, Tetra Spring and Fall and Blackwater Cool Season.

Color Enhancing Diets

A technique that many Koi enthusiasts use prior to showing their fish is to put them in a mud pond to feed on natural vegetation and organisms, which contain pigments that will enhance and intensify their color. Because not everyone is able to do this, Feed Manufacturers have developed diets that contain these color enhancing pigments. Hikari Gold is a high protein daily diet that is supplemented with carotene for outstanding color enhancement in warm water conditions in the 70 to 85F range. Hikari Excel is a premium color enhancing diet that uses pure cultured Spirulina as its color enhancer. This diet is essentially Wheat Germ based making it easy for the fish to digest and assimilate even in cool water temperatures down to 50F. Tetra has a terrific color enhancing diet called Koi Vibrance, which is a highly nutritional diet that also brings out vibrant reds and yellows in Koi and Goldfish. Keystone Koi Pellets and Blackwater Color Enhancingare the most affordable diets, both formulated with the color enhancing properties of the natural pigment from the algae Spirulina.

Growth Diets

Nutritionally speaking, rapid growth is not the most important aspect of a Koi diet, but there are many instances where it is desirable to get the fish up to a larger size as quickly as possible. The thing about growth diets is that they can really only be fed during warm water temperatures when the metabolism of the fish is high enough to handle the heavy inputs of protein. Blackwater Growth is available in a small pellet size, which is perfect for jump starting new Koi in the 4-6” range. Hikari Gold, which was mentioned above for Color Enhancing diet is a high protein daily diet that increases growth rates in warm water temperatures in the 70 -85F range. The most affordable growth diet, which is not intended for everyday use, but can certainly be supplemented, is Keystone Hatcheries 45% Hi Pro Pellets. Since these pellets were designed to be fed to Gamefish, like trout and bass, there are really no guidelines for Koi. However, if you want to give them a try, feed a few times a week when water temperatures are 70F and above. Be sure to feed a staple diet on other days.

Live Feed

There is no substitute for the nutrients found in living food. A terrific way for you to ensure that your fish get ALL the nutrients that they need is to give them a dose of live food at least once a week. This is a feeding technique that we started to use with our brood stock (fish that we use to spawn) about 15 years ago. It proved to be so beneficial that we now feed all of our Koi (except the ones in mud bottom ponds) live food once a week. There is no limit to live food available for Koi and Goldfish, but some examples include Duckweed, Algae, Romaine Lettuce, Earthworms, Shrimp, Grasshoppers, Daphnia, Tubifex Worms, Bloodworms and small Frog Tadpoles. We feed night crawlers and Duckweed frequently.

Seasonal Feeding

As water temperatures go up and down it is important to adjust your feeding patterns accordingly, taking into account the ability of your fish to digest and assimilate the food, and your filters ability to process the waste. Below are some guidelines, but never feed more than your fish can consume within a couple minutes and never feed if your water quality is poor. Koi and Goldfish that are in good condition can go weeks without feeding, so if you have poor water quality, cease all feeding until you have performed water changes and resolved the problems.

Above 85F: These high water temperatures are dangerous because of stress to fish and lower oxygen levels. Do what you can to cool the water through partial water changes and shading. Only feed Wheat Germ based diets in small amounts that the fish will eat in one or two minutes during the morning and/or evening.
70 to 85F: This is the ideal growing water temperature for Koi and Goldfish. Feed Staple, Color and Growth diets in amounts that the fish will consume within a couple minutes up to 4 times a day. Koi and Goldfish have very small stomachs, so they prefer eating small amounts of food frequently rather than large amounts occasionally.
60 to 69F: Reduce feeding frequency to once or twice a day at most. Feed Wheat Germ and Staple diets but avoid Growth diets.
50-59F: Feed no more often than once a day and limit it to Wheat Germ diets. If your fish show no interest in feeding, let them rest.
Below 50F: Do not feed your fish unless they are begging you! This will only happen if the sun has warmed the water and triggered their feeding behavior, or if you have a bad thermometer! If you do feed them, limit it to Wheat Germ diets and only feed once or twice per week. Once the water temperature has dropped to the low 40s, you will do more harm than good by disturbing your fish.

Feeding Program

As mentioned at the beginning of this section, fish benefit from a variety of food sources. There are an unlimited number of potential combinations, but the following is an example of a feeding program, similar to what we feed our Koi: