Food For Koi Fish


Having trouble finding a food that your koi fish will eat? Do you worry about the ingredients in the food that you are using to feed them? Do you feel the need to find a food that is healthy and nutritious for your beautiful koi fish? If so, then we have the perfect solution for you. Introducing our Food For Koi Fish blog. We have a wide variety of articles on topics ranging from general information about koi fish care to reviews of various brands of Koi supper.

Food For Koi Fish

If you have an ecosystem pond you’ll only want to feed your fish a handful of food twice per week. Any more and they can start having health problems.

If you don’t have plants you can feed koi fish as much as they can eat in 5 minutes once per day. Fish don’t have the ability to tell when they’re full so they won’t stop eating as long as there’s food to be had.

The best time to feed your fish is when the pond water is between 50-degrees and 85-degrees Fahrenheit because outside of this range they can’t digest very well. During winter they hibernate so please do not feed them.

Also, get food pellets appropriate for the size of your fish. A better-suited size means your fish can digest more efficiently, making for healthier fish that can grow to their proper size.

What Koi Fish Eat Naturally

In the wild, koi fish eat algae, plants, insects, worms, seeds, and anything they can stir up from the pond’s bottom. They hunt along the pond floor and along the surface. If you have an ecosystem pond they can continue having their natural diet.

This means feeding time is simply a way to bond and have fun with your fish.

What You Can Feed Koi Fish

You can feed koi almost anything people can eat. This includes shrimp, fruit, vegetables, and anything that isn’t high in carbohydrates. Bread and foods like that are hard on your fish’s stomachs. You can also feed them fish food pellets. Make sure they’re the right size.

There are 4 main foods people feed koi fish:

1. Spirulina Algae

These blue-green algae, also called cyanobacterium, live in water and make their own food. They’re very small, only growing up to half a millimeter in length. This algae is free-floating and can be found in lakes with an extremely high pH and very hard water.

Feed koi fish spirulina algae for these benefits:

  • Higher growth rate
  • Improving digestion
  • Boosting the immune system
  • Helping prevent swollen abdomens
  • Enhancing the production of special enzymes that break down fats into energy
  • Bringing out better coloration due to carotene pigments found in the algae

2. Wheat Germ

Don’t worry it’s not the bad kind of germ. This is the part of wheat that sprouts and grows into a new plant, the wheat seed if you will. Experiments have shown wheat germ can help goldfish and koi grow faster. It’s also a natural source of vitamin E which improves blood circulation, increases oxygen and nutrient flow, helps promote balanced growth, and aids in fighting off disease.

3. Brine Shrimp

Here’s a fancy science word for you: bio-enrichment. Brine shrimp filter water by eating anything in it they can, which isn’t much due to their small size. The nutrients they eat pass on to the fish they are eaten by, which is the process known as bio-enrichment. Brine shrimp are especially good for feeding recently hatched koi fish.

4. Fish Food

Small and baby koi prefer flake fish food, the smallest form. Pellets are good for the average-size koi while larger koi prefer bars of fish food. Most have plenty of proteins, a small number of fats, and essential vitamins & nutrients.

Some other favorites include worms, larvae, tadpoles, shrimp, and clams.

What Not To Feed Koi Fish

Don’t feed koi fish anything high in carbohydrates. You should also avoid feeding them white bread, peas, and corn. Koi fish have a hard time digesting carbs.

Don’t feed them anything you catch in the wild either. This includes fish, bugs, frogs, and everything else. They could have parasites or diseases.

Grains aren’t the best food for koi. They tend to be very fattening, which is good if your fish start losing weight. If you decide to feed them pasta or rice you’ll need to cook them without salt first. Otherwise, the food could expand inside your koi.

Of course, these foods should not be the basis for their diet. They have little nutritional value for koi.

How To Feed Koi Fish

Cut up any larger foods into bite-sized pieces. Toss one handful into the pond. Let the koi eat as much as you can see before the next handful. Any food left in the pond needs removing. This way it doesn’t break down and lower the water quality.

Key Foods in Koi Fish Diet

Koi fish are staples in ponds and hotel lobbies across the world. Literally translated as “brocaded carp,” modern Japanese koi originated in Niigata, Japan, in the 19th century. Modern koi were originally bred from the Amur carp, a species native to East Asia that has been bred for centuries, primarily as a food source dating back to the 5th century BC.

Thankfully, these beautifully colored fish aren’t used for food anymore but are kept as decorative pets. There are dozens of varieties of koi, each with its own markings and traits. As a common pet, you might be wondering what koi fish eat, especially if you are considering some for your pond. Let’s look at what koi eat and learn how koi thrive in different seasons when food is scarce.

What do koi fish eat?

Koi fish swimming in the pond.
Koi fish are omnivores that eat worms, larvae, seeds, and algaePokkO/

Koi fish eat worms, larvae, seeds, algae, insects, and small crustaceans. Technically omnivores, they will eat pretty much anything they can fit in their mouths. Koi don’t have teeth in their circular mouths, making it hard for them to bite or tear. Instead, they have fleshy mouths that are more designed for sucking in food.

Koi are known as “benthic feeders”. Benthic feeders live near the bottom of a body of water and subsist off of what they can find there. More commonly known as bottom feeders, koi sweep the sediment bed of the body of water they live in, searching for any food they can find. While they mostly eat from the bottom of sediment beds, modern domestication has allowed them to eat floating debris and food. This makes fish feedings a regular aspect of owning koi.

Since they have no teeth, many people feed koi food pellets with their bare hands. As the koi feeds, it often sucks the person’s fingers and is quite ticklish. You don’t have to be worried about swimming or placing your hands in water where koi are present as they aren’t harmful to humans.

When koi are introduced into wild habitats, they are known to be quite destructive. Their destructive nature comes from the way they eat. As they glide along the bottom of a waterway, they cause debris and sediment to loosen and unsettle. Known as “turbidity,” the unsettled sediment reduces light penetration and stops plants from taking root, often killing them. Additionally, the extra sediment can be so severe that humans and animals alike can’t drink the water.

Koi are often deliberately released into human-made lakes and golf ponds to help reduce larvae populations and keep plant life down.

A complete list of the foods koi fish eat:

Here is a list of the most common foods a koi will eat in a pond or natural environment:

  • algae
  • silkworm pupae
  • bloodworms
  • earthworms
  • mosquito larvae
  • tadpoles
  • duckweed
  • hyacinths

Although these are the most common foods that a koi fish will eat, they aren’t very picky about their diet.

Who competes with koi fish for food?

What do catfish eat - catfish feeding
Catfish and other bottom feeders compete with koi fish for food in the wild.Rostislav Stefanek/

Since koi live in pond ecosystems, they constantly compete with other fish. In a domesticated and human-built environment, koi don’t have many competitors, however, as the food source (humans) provide food in the form of pellets or feed.

In a wild environment, koi often live with other carp, killifish, and minnows, although they may eat them if they are small enough. They are also found with large fish commonly seen in lakes and streams, like catfish, bass, sunfish, or perch. Since catfish are the closest to the koi in terms of environmental niches (aside from other carp), they could be the fish most often competing with koi in the wild.

How much do koi fish eat?

Koi fish eat based upon the ambient water temperature. The colder the water, the less active they are. The warmer the water, the more active they are. In domesticated situations, koi will usually eat 1-4% of their body weight. When in the wild, koi are always looking for food, sweeping the bottom and sucking up anything they come across.

For domesticated koi, it’s usually better to underfeed than to overfeed as it is more likely to cause health issues.

The ideal diet for koi is 32-36% protein and 3-9% fat. Additionally, you want to ensure that any feed given to koi is low in phosphorus. Too much in a pond ecosystem will promote unchecked algae growth and cause further health problems to koi and any other fish species.

What do koi fish eat in the different seasons?

Beautiful Koi in a pond in Japan.
In domesticated situations, koi will usually eat 1-4% of their body weight.

Koi are poikilothermic, meaning they don’t have a natural ability to regulate their body temperature (like a human can, for example). As a result, their activity levels directly correlate to the ambient temperature of the water, in turn affecting their eating habits from season to season.

During warm seasons where the water is between 71°F and 85°F degrees, a high protein diet is recommended as they are likely to be moving, growing, and altogether more active. Additionally, koi eat multiple times a day, up to a maximum of four.

During the cooler winter seasons, when the water is between 41˚F and 60˚F, a carb-based diet of wheat germ is recommended as long-term energy and conservation is more needed.

When the temperate drops below 40˚F, koi don’t eat and enter a state of hibernation known as torpor. Torpor drastically reduces their energy needs, decreases their metabolism, and slows their bodily functions. This fantastic adaptation allows koi to live in places that get below freezing in the winter.

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