A Guide On Raising Koi Fish For Aquaponics Systems

If you're planning on starting your own aquaponics system and wondering if you can use koi, you've come to the right place. This article will share all the essential information you need to know about raising Koi in an aquaponics system. 

For many years, the Japanese Koi have always been valued because of their ability to provide beauty in ponds and other backyard living spaces. This is one reason why many aquaponics growers have chosen to raise this colorful fish in their aquaponics systems. Although inedible, Koi fish are versatile and have the ability to survive in a wide range of water conditions. 

Different Varieties of Koi 

With more than a hundred koi varieties available, choosing the best Koi for your aquaponics system might be confusing. So in order to choose the right variety, consider the price and the overall resilience of the breed. Below are the eight koi varieties that are considered best for aquaponics systems.

  1. Kohaku
  2. Utsurimono
  3. Koromo
  4. Kawarimono
  5. Hikari Muji
  6. Shusui
  7. Bekko
  8. Asagi

What is the Best Koi Variety for Aquaponics?

The Kohaku koi is the recommended variety for aquaponics because of its solid white body color with red markings appealing to the eyes. This variety is also hardy, which is excellent for aquaponics. 

How Big Do Koi Fish Get?

A koi fish can grow up to 36 inches long (3 feet). Although your koi fish don't always end up to this size, they can still take up a lot of space. So you need to consider the size of your fish tank or pond before starting to raise koi.


Fish Feeding In Aquaponics

The Advantages and Disadvantages of Raising Koi in Aquaponics Systems

Here are the advantages and disadvantages of using koi in your aquaponics system.

Advantages of raising koi:

1. Disease and parasite resistant

Koi is great for aquaponics systems because of its resiliency against diseases and parasites. 

2. Tolerant of a wide range of water temperatures

Koi can endure a wide range of water temperatures, 1-32°C (34-90°F), which is excellent, especially if you live in a place where the temperature fluctuates.

3. Colorful and attractive fish species

Koi can enhance the beauty of your home, office, or garden.

4. Long lifespan

Koi can reach up to 30 years. This is good for aquaponics systems because you will not need to buy new fish additions often. 

5. Koi are not fussy eaters.

Koi eat natural substances such as algae and food waste, so they only require very little fish food.

Disadvantages of raising koi:

1. Inedible

Koi are not edible fish, which is a disadvantage for aquaponics growers. It is because aquaponics systems are designed to produce two types of healthy foods: fish and vegetables. 

2. Requires large fish tank

Koi are large fish species, which means they need a large fish tank to reach optimal growth, which could be an issue for aquaponics growers with limited space.

Requirements for Raising Koi in Aquaponics Systems

Below are the guidelines you can use to ensure you are raising a healthy koi fish species in your aquaponics setup.

Stocking density: Most aquaponics growers limit one koi for every 200 gallons of the fish tank. The stocking density influences the health of your koi as disease outbreaks usually happen on heavily stocked ponds or fish tanks. 

Tank size:Koi are huge and slow-moving fish with a long lifespan. As your fish mature, they will require more space to survive. So the more fish you have, the more space they will need. For a starter, a tank or a pond of at least 10 feet deep with a capacity of more than 1000 gallons of water is the ideal size for 5-g koi. With this being said, it is not advisable to start your aquaponics system with fully grown, mature fish. Start with koi fingerlings instead, as this will allow your fish to become more accustomed to their new environment. 

Water temperature: The ideal water temperature range for koi is 59 - 77 °F (15-25°C).

Sunlight:Sunlight can help keep koi healthy. The warm water can help boost the fish's immune system. Sunlight is essential for koi, but you should also provide them with a shaded area to minimize too much sun exposure.

pH Level: The ideal pH range for koi is 7.5 to 8.

Oxygen requirements:The ideal oxygen level for koi is 7mg/L.

Fish diet and nutritional requirements: Koi are omnivores, which means they will eat both plant and animal matter like green vegetables and worms. High-quality fish feed is also recommended for their optimum growth. 

Feeding frequency: The rule of thumb for koi is one meal per day. Feed them as much as they can eat within five minutes and remove any uneaten food from the fish tank. The temperature will also affect the fish's eating habits, which means that you should feed them more in the summer and less during winter.

Setting Up a Koi Fish Habitat in Your Tank or Pond

Koi fish live in water that doesn't move much in the wild. Try recreating these living conditions as best as possible to have a thriving koi aquaponics system. Creating a perfect koi habitat is easy because you can still give them the best life in their pond, aquarium, or fish tank.

Koi Pond or Pond Setup:

  • Koi grow quickly and get very large, so consider getting a large fish tank, aquarium, or pond where your koi fish will have enough space. 
  • Put your fish tank in a quiet area out of direct sunlight.
  • Cover the tank with a hood to reduce evaporation and keep the fish from leaping out.
  • Quarantine the new fish in separate water for 3 to 4 weeks to make sure they are healthy and free from diseases before transferring them to the fish tank or pond. 
  •  To transfer a new koi to the tank or pond, float them in the water inside their bag for a few minutes (10 minutes or more), so they can acclimate to the new water temperature.
  • Whether indoors or outdoors, do not add more than three new koi at a time.

Heat and Light

  • Outdoor koi are hardy and hibernate under the ice during winter as long as their pond is deep enough not to freeze entirely. Koi will not survive on solid ice.
  • Shade your koi pond or tank partially to prevent direct sunlight exposure.
  • An indoor koi prefers a water temperature between 65-75°F.
  • You can install a light above the tank to illuminate it for 8 to 12 hours a day. 

Common Diseases for Koi

Although koi are disease resistant, they can still have diseases if they live in less desirable conditions. One of the most common diseases for koi is Ich or white spot disease. Ich is a protozoan that starts growing in the tank and clings to the gills of a mature koi. The signs of ich disease are tiny white salt-like grains. Other diseases to watch out for are dropsy and tail rot. To learn more about fish diseases, read our article, "Fish Health and Disease in Aquaponics." 


Koi in A Pond

Starting Your Koi Pond Aquaponics System

If you have an existing pond or are planning to build a pond aquaponics system. Here are the different options you can implement for using your pond to incorporate aquaponics and grow vegetables.

  • Adding a Growing Raft

Grow vegetables in your pond by implementing the raft (dwc) system of aquaponics. You can do this by using floating rafts. These floating rafts are made with water-resistant materials that ensure durability and longevity.

However, if you are a do-it-yourself person, you can DIY your floating rafts using Styrofoam. You can do this by taking a piece of Styrofoam, drilling holes, and using a net cup to hold the plants, insert the plants, and let them float in your pond. 

One thing to keep in mind about using floating rafts in your pond aquaponics system is that koi like to nibble on plant roots. So it is recommended to put some mesh protection under your raft to keep fish from eating your plant roots. One alternative is to put each plant into a large mesh pot containing supporting materials, like clay pebbles, to hold the roots. 

  • Adding a Grow bed

If you want a larger growing area to increase the number of plants you can grow, you can make a growing area outside of the pond. There are several options for adding grow beds, but you will need a grow bed (the size of your choice), pump, pipes for piping, a siphon, and grow media to support plant roots and keep the plant up. 

The pump will move the pond water into the grow bed, where plant roots absorb the nutrients while at the same time cleaning the water before it flows back into the pond. The moving water also helps oxygenate the water in the pond. It would help to position your grow bed slightly higher than the pond to allow gravity to drain the water back from the grow bed into the pond.


Koi is one of the most popular fish used in aquaponics systems because it is a hardy fish that can tolerate a wide range of temperatures. They are also a colorful fish species that can add beauty to your home or backyard. Using koi in your aquaponics system can be an easy and effective way to run a system that produces plenty of organic and fresh food for you and your family. Thank you for reading our article. Feel free to leave your comment below. 



1 Response

Serajul T. Ali

Serajul T. Ali

December 13, 2022

Excellent texture , easy to understand, please continue such an articles so we can be benefited.

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