Last update: November 4, 2022

What Do Koi Fish Eat And How To Take Care Of Them?

Most people who have ponds in their backyard usually keep a couple of Koi to brighten up the outdoor space.

They are some of the most common and also well-known fish to keep in outdoor garden ponds. They were first bred in Japan and are highly prized and even can be seen portrayed in many myths and artwork.

While they are related to goldfish directly, you should never assume that they need the same level of care. These fish will not do well in a tank, and they need to be in an outdoor pond.

So if you are ready to adopt a few Koi and have them live in your garden pond, keep reading as we’ll discuss everything you need to know about this beautiful species of fish.

You’ve probably heard the word Koi being mentioned when people refer to the backyard ponds. This is because Koi fish is one of the most common and popular types of fish to have in an outdoor pond. This is because Koi fish are available in a variety of different and beautiful colors that will bring an instant facelift to any outdoor water feature.

Where Do They Come from?

group of koi fish

Descending from the carp, Koi is an ornamental species of fish then. The Chinese farmed carp in rice paddies in the 1600s, and then the practice traveled to Japan. However, the Japanese noticed the bright color variations in the Koi and decided to breed them for their aesthetic appeal.

Koi used to only be available in varieties of white, red, blue, and black. However, since being bred, they are now available in different combinations of all colors in the rainbow. The first Koi was bred exclusively in Japan. It was only until the 1900s that Koi began to breed in parts of the United Kingdom, the United States, and Europe.

1. Interesting Facts about Koi

Koi can grow up to 2 to 3 feet and longer. Some of the factors that influence its size are the size of the pond, the food it is fed, the number of fish sharing the space, the age of the fish as well as the water quality.

So before setting up your Koi pond, ensure that you consult with a seasoned Koi pond builder who will guide you on how to go about creating the correct environment for your Koi.

Koi are also social fish, which basically means that they love company. So they may be kept with other Koi or goldfish since they are docile in nature. Why also change color throughout their lives. Many of these changes are a result of pigments in their food.

Another interesting fact is that some Koi may turn white as they age.

They can also survive under a layer of ice. While they do need a small opening in the ice to get oxygen, they are very well capable of surviving under a thin layer of ice. However, the only exception to this is if the water gets too cold or freezes way below the surface.

Most Koi live for approximately 20 to 30 years. However, the Koi species itself has survived for more than 200 years. However, in order to enjoy a long and healthy life, you need to ensure they have a healthy environment that has good filtration and good water quality.

There shouldn’t be any sharp edges in the pond, as this can lead to them injuring themselves. They also need appropriate chemical levels, temperature, and good nutrition, as well as no stress. Some causes of stress include poor water quality, crowding, toxic chemicals, and parasites in the pond water.

What Do Koi Fish Eat?

man gives food to koi fish

If you’re one of those pet owners who enjoy sneaking some table scraps under the table, then you’re going to love feeding your Koi. Perhaps one of the best parts about owning Koi fish eat naturally is that you can quickly teach them to eat right out of your hand. So this makes feeding time fun and interactive.

Koi are naturally omnivorous, so they’ll eat anything from plants and algae to shrimp and even other small fish. Like us, they also need a range of foods and nutrients to remain healthy. So believe it or not, your Koi needs plenty of vitamins, proteins, minerals, carbohydrates, and fats provided in the right balance, of course.

Like us, Koi as well, don’t need too many carbs as it’s bad for their health. Some other ingredients will enhance the color of your fish, such as Spirulina. So let’s take a closer look at the foods that you can feed your Koi.

1. Leafy Greens and Lettuce

We all have a bit of leftover lettuce every now and again when making that Saturday lunch. It’s good to know then that lettuce makes a great and delicious treat for Koi, and you may even have the privilege of watching several Koi compete with each other or other work together to rip the pieces apart.

However, one point to take note of is that lettuce is not typically high in nutritional value so be sure not to feed too much of it to your Koi as they still need room for other valuable nutrients. Spinach is also a good treat for your Koi; however, you should never ever serve any leafy greens with salad dressing or spices to these fish as it could be toxic to their health.

2. Citrus and grapefruit

For some reason, Koi are especially fond of grapefruit; however, they will eat a range of orange and lemon slices too. To feed them to your Koi, simply cut them into sections and let them float at the top of the pot.

Alternatively, if you want to let the kids have some fun let them hold out a piece over the pond and allow the fish to snatch it right out of their hands. However, never leave any skin or rind in the pond as it could clog the filter.

3. Cheerios

if you really want the kids to have fun, then you let them feed the Koi their breakfast. Cheerios are low sugar and high nutrients and they also float nicely on the top of the pond. However, they still contain carbs so it should be fed in moderation.

4. Garlic

While garlic is toxic to dogs and other household pets, it’s a nutritious and tasty treat for Koi. Not only does it boost the immune system, but the Koi can’t seem to get enough of it. To serve it to your Koi, chop up pieces of raw garlic or soak the pellets in garlic and sprinkle them over the pond.

How Long Do Koi Fish Live?

When it comes to regular or domestic Koi, which is the type of Koi that most people have, the average life span is 15 years. These types of Koi don’t grow to be very large and usually end up a foot long at a maximum.

However, they are less of a commitment than Japanese Koi, which live twice as long as domestic ones. The average lifespan of a Japanese boy is yes. However, you should also be reminded that several factors play a role in this difference in longevity, such as genetics and feeding.

Koi Fish Maintenance

koi fish macro

When you purchase Koi from a pet store, it is important that you quarantine it before putting it together with the other fish. So you should observe the Koi in the tank for approximately 14 to 21 days. Watch them carefully, so you notice if any problems develop.

It is also suggested that you change the water every 2 to 3 days if it is working without a filtration system.

You should also add salt to accommodate water changes accordingly. Feed your new Koi easily digestible food on a daily basis.

Nitrate and ammonia should be checked every single day as well, as it is important to keep a careful eye on nitrate levels so that you can ascertain whether your fish are stressed or not.


Purchasing Koi is an exciting and fun experience; however, it’s also one that should be approached with caution. There’s a right way and a wrong way to care for your Koi.

There are foods that they enjoy, which are perfectly safe for them, and there are also foods that you should not feed your fish. So in order to be a good pet owner, do your research and ensure that you know everything you possibly can about Koi.

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

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