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Caring for Koi in Aquaponics Systems (Easy Guide)

Caring For Koi In Aquaponics Systems

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For centuries Japanese Koi ponds have been highly regarded for their beauty and ability to provide peaceful settings in backyard living spaces. So it’s only natural that many gardeners have turned to the colorful fish to help bring the same magic to their aquaponics setups. Although inedible, Koi are versatile, bringing both hardiness and the ability to survive in a wide range of conditions. Best of all, caring for Koi in aquaponics systems is much easier than you think.

In this article, you will learn some important information on how to raise Koi in an aquaponics setup.

Why Raise Koi in Aquaponics Systems?

Why Raise Koi in Aquaponics Systems

Koi are among the most popular freshwater fish types best suited for aquaponics for several reasons. An aquaponics setup that uses Koi is often successful because these fish are highly adaptable. They have a long life and can easily reproduce within your system. Just like their relatives, the carp and goldfish, Koi is fairly resistant to parasites and disease. This doesn’t pose a problem when you plan to keep them in close quarters.

Koi are omnivorous and are not picky when it comes to food. Because they can feed on things such as algae, plant matter, and fallen debris, Koi have a natural degree of independence that many other fish breeds do not have. As a result, you may experience a slight reduction in feeding costs as well as less frequent tank maintenance.

Koi Varieties

With over a hundred known types of Koi, you can find colors including white, black, orange, yellow, blue, and many others with wonderful displays of exotic skin tone patterns.

When choosing the Koi for your aquaponics system, you will want to consider both price and the overall resilience of the breed. For example, Ghost Koi are ideal for people that are just beginning with aquaponics because they are relatively inexpensive. On the other hand, breeds such as Kohaku are popular choices due to both their appearance and overall toughness.

Requirements for Caring for Koi in Aquaponics Systems

Requirements for Caring for Koi in Aquaponics Systems

Below are the general guidelines you can use to ensure you maintain a thriving Koi population in your aquaponics setup.

Stocking density 

Most aquaponic gardeners limit themselves to one koi for every 200 gallons of tank water. This is already a decent stocking density, provided you have additional aeration and don’t mind regular maintenance.

Tank size 

Getting a 1000-gallon tank will be enough to have 6-5 koi

Water temperature

Koi can thrive in a wide range of water temperatures, from 59 t0 77 deg F. But keep in mind their immune systems may fail if temperatures reach 50 deg.


Unlike trout, Koi can benefit from sunlight exposure. In fact, it can keep them healthier. The warmth of the water can help boost the fish’s immune system. However, while sunlight is important in your koi pond, you should provide a shaded area to minimize direct sun exposure.

pH Level

Koi prefer slightly alkaline waters, so a pH level of 7.5 is ideal. A neutral pH of 7 won’t harm the fish, but if it drops down to the acidic level, it can be stressful for them.

Oxygen requirements 

To ensure the healthy growth of Koi and support reproduction, your pond should have a minimum dissolved oxygen concentration of 6mg per liter of water. An oxygen level of 7mg/L is desirable, and anything higher is ideal.

Best breeds for aquaponics

The most popular breed of Koi that is suitable for your aquaponics system is the Gosanke breed, which comprises the aforementioned Kohaku, Showa Sanshoku, and Taisho Sanshoku, and varieties.

Fish diet/nutrient requirements 

As an omnivore, koi are not difficult to feed as they will eat plant and animal matter. But for optimum growth, giving high-quality feed is recommended. For the main portion of their diet, you can feed flakes and pellets that provide a well-balanced diet. They can also eat green vegetables or enjoy worms occasionally. 

Feeding frequency 

As a general rule of thumb, your Koi should only eat once per day. You can give as much as they can eat within five minutes. Any food that has not been eaten should be scooped out to maintain water quality. 

Temperature will also be a factor to consider when feeding koi. The fish’s digestive ability can either be sped up by heat or impaired by cold. For this reason, you  may need to give more in summer or less in winter. Some koi owners don’t even give anything in winter, which is fine since koi can go on without eating the entire season.

How to clean the tank 

Caring for Koi in aquaponics systems requires regularly tank cleaning to prevent the overgrowth of algae. Your Koi may eat the algae, but it is necessary to take steps to avoid algae blooms. To maintain your koi tank, be sure to check and change out filters and monitor algae levels.

Common diseases

There are different diseases and parasites that can affect your Koi, especially when they are living in less desirable conditions. One of the most common diseases is Ich or white spot disease. 

Ich is a protozoan that starts growing in the tank but later on clings to the gills of a mature Koi. When observing your Koi, you might see tiny, white salt-like grains, which indicate the presence of the parasite. To remedy this, move the affected Koi to a quarantine tank and raise the salt concentration of the water to 0.5 percent gradually over the next few days. The quarantine period should last for two weeks.

Other diseases to watch out for include dropsy, tail rot, mouth rot, and Chilodonella. Check out this guide on different diseases found in Koi and their treatments.

Aquaponics plants best suited for 

Because they are hardy species that tolerate a variety of conditions, caring for Koi in aquaponics systems lets you grow many kinds of crops, including blackberries, strawberries, marjoram, and radishes.

When to rotate fish in and out of the tank 

When introducing new fish to the tank, make sure to quarantine them first. Add Koi gradually, as doing otherwise can raise ammonia levels drastically, resulting in an unfavorable environment for your fish and plants.

Water filters 

Having both mechanical and biological filters can be beneficial to your tank if you have a large one. This can make your tank waters crystal clear, and you can have some peace of mind that you have a healthy and clean environment for your fish. However, if you have to choose just one type of filter, go for a biological filter system.

As for the size, it is generally recommended to have a filter that is double the size of your tank. For instance, you have a 1000-gallon tank, which means you should install a filter that can support 2000 gallons. At the same time, filter size should also depend on the fish population and the amount of waste they produce.

Can they be mixed with other breeds?

Koi can easily co-exist with other fish, but only those that are considered low-risk – also known as small fish species. Standard goldfish can live with Koi in the same tank but not the fancy ones as they tend to be smaller and slower, which makes them easy targets for Koi.


If you plan to breed your Koi, you should wait until the waters are warm enough, sometime in late spring or early summer. You should have a dedicated mating tank with at least one male and one female. Watch this video on how you can identify a male and female Koi.

The Campbells love finding sustainable and fun ways to increase their independence from traditional brick and motor supermarkets. Aquaponics provides a full lifecycle food source for families and a great hobby. #aquaponicslifestyle

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