What Does Koi Fish Eat in an Aquarium? 

Koi fish is one of the most popular aquarium breeds. There are various reasons for having them in your aquarium.

They are beautiful and lively, and having them in your aquarium can add to the beauty of your living space. However, to make sure your Koi fish stay healthy and live long, you need to be careful about what they eat.

The following guidelines will help you with what to feed your Koi fish and When.

Let’s sink right in.

What Do Koi Fish Eat?

If you have had Koi fish in your aquarium, you can understand that they are natural omnivores. Be it plants or meat, the Koi fish will try to eat anything that is thrown their way. Therefore, as a responsible Koi owner, you must feed them only what they are supposed to eat.

To stay healthy, active, and colorful, the Koi must eat the right mix of plants and proteins. A balanced diet that is rich in minerals and vitamins in what they need to grow.

Let’s take a look at some of the things your Koi fish should eat to stay healthy.

Kinds of Food Koi Fish Should Eat

Before we discuss the food items, we should consider whether their food should sink or float. Each has its pros and cons.

Sinking Food

As the name suggests, sinking food fall to the bottom of the aquarium. Therefore, it is easy for your Koi fish to catch and eat. The mouth of a Koi fish is faced downward, and they tend to eat the worms found in the mud.

Fetching food in a downward direction is the natural way a Koi fish eats. Therefore, it is an efficient way of feeding them.

Using this technique, you don’t have to put in a lot of food, for there is little left behind, which can affect the tank’s balance.

However, there are some downsides. If you fail to watch your Koi fish eat, chances are they won’t. When your Koi fish fail to eat, it won’t get the nutrition, it needs to stay healthy.

Floating Food

Most of the Koi food available in the marketplace is the one that floats atop the surface. Its easy availability is the reason hobbyists commonly use it.

The best thing about floating Koi food is that you can watch your Koi fish swarm to have a go at it. Watching them eat is one of the best things about keeping Koi as pets.

Furthermore, another benefit of floating Koi food is that it allows you to keep an eye on your fish. Watching your fish regularly helps determine whether or not something is wrong.

Not only does floating food helps you seek if your fish are eating, but it also enables you to check for injuries. If you spot a fish that doesn’t eat, you can observe them for illness.

The downside of floating Koi food is that it quickly gets sunk into the water. As a result, Koi might have difficulty eating it. However, with a high-quality air pump, you can keep floating food from sinking in.

Food Items Koi Fish Should Eat

As discussed above, just like any other living creature, Koi fish also need a variety of nutrients.

Here are some ingredients to consider when deciding what to feed your Koi fish.

Brine Shrimp

As discussed in the initial paragraphs, Koi are omnivores.

This means that they need enough protein to stay fit. One of the best diets for your Koi fish is Brine shrimp.

Not only does it contain enough protein, but a host of other nutrients your Koi fish need.

Brine shrimp is the perfect food item, during periods when Koi are most active.

For example, newborn Koi fish need sufficient protein for growth, while adults need it during the summer months when their metabolism is quick.

Spirulina algae

This kind of algae is bluish-green. It tends to grow in hard waters, where the PH level is naturally high.

Unlike other kinds of algae, this type is small in size and tends to float. Furthermore, it also does not grow on rocks, which is why it is easy for your Koi fish to fetch.

Spirulina Algae is suitable for your Koi fish for several different reasons. It enhances the digestion process in Koi fish, discourages bloating, and promotes immunity, thus keeping illnesses at bay.

Wheat Germ

The name might confuse you, but wheat germ has nothing to do with real germs. Instead, it is the seed of the wheat plants.

Wheat germs contribute to proper growth in Koi fish and are also beneficial for a variety of different reasons.

Besides being a rich source of vitamin E, wheat germ also improves Koi’s immune system and promotes circulation and oxygenation.

Unlike the summer months, in the colder months, Koi’s digestion slows down. This is where Wheat germs help them digest food properly and not develop any metabolic problems.

Wheat germ is also a source of good fat, which is easy to digest and help your Koi fish as they hibernate.


Just like any other pet, Koi fish also love having treats.

The Koi fish list of treats includes things like watermelon, orange slices, garlic, broccoli, shrimps, and worms.

However, too many treats can be harmful to your Koi’s health, and must only be fed in moderation.

Also read: Why is My Koi Fish Not Eating?

What Not to Feed Your Koi Fish

Up until now, we have discussed the kinds of foods, and food items your Koi can eat. Now, let’s talk about the food items that are potentially harmful to your Koi fish.

To keep your Koi fish healthy, make sure you keep them away from low-quality food with little nutritional value. The reason being: those food items lack the proteins and minerals your Koi fish require to grow and stay and healthy.

Furthermore, refrain from feeding to your Koi fish, foods that are rich in carbs.

Corn, bread, and peas are rich in carbs, and therefore, must not be fed to your Koi fish. These foods are difficult to digest, and if eaten in access, can make your Koi’s health break down quickly.

What Is the Right Time to Feed Koi Fish?

Most Koi fish Owners tend to keep them in outdoor ponds. Therefore, the temperature must be taken care of when feeding them.

Just like any other fish, Koi fish are also cold-blooded. Consequently, the temperature of their environment has a direct impact on their metabolism. Therefore, their metabolism depends upon what season and climate it is.

You may not know, but Koi fish eat little or no food when the surrounding temperature falls below 48 degrees. Try not to feed your Koi fish when the temperatures are low.

Chances are they won’t eat, and even if they do, their health might get affected. Furthermore, trying to feed them during winter would be a waste of food, which is expensive to buy.

Moreover, the temperature in the surrounding also determines what your Koi fish should eat. The goal here is to make sure your Koi digests what it eats, without becoming sick.

For example, in temperatures between 45 and 60 degrees, fatty foods are perfect for Koi fish. As discussed above, wheat germ is a rich source of fat.

When the temperature goes above 64 degrees, Koi need more protein. So, try mixing the food with vegetables and fruit.

During the summer months, try to monitor the temperature. If the temperature goes above 88 degrees, your Koi can easily get stressed.

When the water gets too hot, it loses a lot of oxygen, thus making it difficult for your Koi fish to breathe. To eliminate this issue, try adding ammonia to the fish tank.

Continue to feed your Koi fish, but the portions should be relatively small, especially if the temperature exceeds 88 degrees.

How Much Should Koi Fish Eat?

The amount of food given to the Koi depends upon the number of Fish in the aquarium, as well as what time it is.

An easy way out would be to go for the five-minute rule. Try to feed your Koi as much as you can within five minutes.

After that, remove all the food from the water, and make them starve until the next serving. Make sure you get the balance right, but it is always good to underfeed than to overfeed.

Underfeeding might only affect the growth of your Fish, but overfeeding tends to pollute the water with bacteria, which is potentially harmful to your Fish.

A polluted fish tank has lesser oxygen and is unhealthy for your Koi fish.


During the summer months, a Koi fish’s metabolism is fast. Therefore, they must be fed sufficient amounts of protein.

Following the five minute rule, they must be fed a couple of times a day.

However, with a drop in temperature must be fed a little less. If the temperature goes below 48 degrees in winter, refrain from feeding them.

Lastly, refrain from feeding them large amounts of treats and foods that lack nutrition, such as corn, bread, and peas.

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