Are Koi Fish Good for Aquaponics? Detailed Guide!

Starting your first aquaponics system can be exciting, but it’s important that you know what you’re doing.

Take the time to do ample research, and decide beforehand what kind of fauna and flora you want to feature in your aquaponics system.

One question you may be wondering is if koi fish are suitable for your aquaponics system.

This article will tell you everything you need to know about the best way to raise healthy, thriving koi fish in an aquaponics system.

Best Koi Fish for Aquaponics

There are several different kinds of koi fish. When building an aquaponics system, it’s necessary to know which one is the most suitable for such an environment.

The eight different types of koi fish include:

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

Most aquaponics experts recommend Kohaku Kui as the best variety of koi fish to include in an aquaponics system, as they tend to be the most resilient.

Not to mention, their unique red and white coloration will complement the greenery of your aquaponics system nicely.

Building The Right Size Aquaponics System

Do you already have dimensions for your aquaponics system in mind? It’s important to know that koi fish can grow quite large, with some reaching as big as 3ft in length.

Is your aquaponics system big enough to comfortably house enough koi fish? Do they have the space they need to thrive and grow?

Or will you perhaps need to eventually expand your aquaponics system, when the time comes?

These are all questions you should have the answer to before you commit to anything.

Advantages/Disadvantages of Keeping Koi Fish in the Aquaponics System

Before you start keeping koi fish in your aquaponics system, you should be aware of the advantages and disadvantages of doing so.

This article will help break them down for you, so you can make an informed decision.

The Advantages

  • Koi fish are hardy fish. They tend to be resistant to parasites and diseases.
  • Koi can withstand a range of water of temperatures, allowing you to grow diverse flora in your aquaponics system.
  • Koi fish live longer than most other commonly kept pet fish species. Some live for up to 30 years, so you won’t need to keep buying new fish.
  • The koi will happily eat the algae and wasted plant matter that grows in your aquaponics system.

The Disadvantages

  • Most people maintain aquaponics systems for the sake of growing edible plants and seafood. Koi fish aren’t edible, meaning they’ll take up space in your aquaponics system and only be decorative.
  • Koi fish grow quickly and recover plenty of space. You might end up having to regularly upgrade your aquaponics system.

What You Should Know Before Keeping Koi Fish in An Aquaponics System

There are a few basic guidelines you should follow to ensure that the koi fish that live in your aquaponics system is healthy and thriving.


How many koi fish should you keep in a single aquaponics system? Most experts believe you should have one koi fish for every 200 gallons of water.

Over-stocked ponds can lead to diseased or malnourished koi, as they’ll be fighting for space and food.

Tank Size

Aquaponics experts say that the ideal dimensions for an aquaponics tank featuring koi fish are a 1000-gallon tank, with a depth of 10ft.


Kois are omnivorous creatures.

That means they’ll happily eat worms and plant matter present in your aquaponics system, but you should still supply them with traditional, packaged fish food.


It is recommended that you get young koi fish rather than fully mature ones.

Young koi will be able to adjust better to their new environment in your aquaponics system.

Natural Light

Your koi require sunlight to remain healthy and happy, as it helps to keep their immune system functioning properly.

However, too much direct sunlight can also be harmful, so provide them with a portion of adequate shade.


It’s important to provide your koi fish with an ideal temperature. Generally, a temperature ranging from 59 °F to 77 °F (15°C to 25°C) is preferred.

As the weather changes, you will need to continuously monitor the temperature of the water.

pH Levels

The recommended pH level for an aquaponics system featuring a healthy population of koi fish is 7.5-8 pH.

How To Set Up Koi Fish in An Aquaponics System

When creating an aquaponics system that is suitable for koi fish, the best thing you can do is to create an environment as close to their natural habitat as possible.

To set up a successful aquaponics system, you must first understand the various components in the system itself.

Your grow bed should be at least 15 inches high, with 12 inches of the bed submerged in water.

Next, you need to decide on what kind of substrate, or ‘media’ you want to use in your grow bed.

In the case of a grow bed, media refers to the kinds of rocks you intend to use. These can include clay, igneous rock, and river rocks.

Make sure your grow bed is properly connected to your body of water, using PVC piping.

This connection must remain uninterrupted, so your plants can grow properly.

Next, you’ll need to install a bell siphon into your grow bed, so that excess water can be drained properly, rather than allowing the grow bed to overflow.

Certain flora will have difficulty growing if water levels rise too high. As the bell siphon causes water levels to rise and fall steadily, nutrients will be spread evenly across the aquaponics system.

A split pump bypass will allow you to tend to your koi fish without ever tampering with the rest of your aquaponics system.

What Should You Grow in Your Aquaponics System?

If you’ve designed your aquaponics system around your population of koi, there will be certain plants that will be better suited to the environment of the system than others.

What that means, is that you’ll need to carefully choose what kind of flora you’d like to grow.

The most popular vegetation grown in aquaponics systems include Tomatoes, Lettuce, Bell Peppers, Herbs, Watercress, Water Spinach, Chives, Mint, Basil, Cucumbers, Squash, Beans, Peas, Broccoli, Cabbage, and Cauliflower.

Experienced aquaponics enthusiasts advise that water spinach is the easiest plant to grow, for beginners.

All of these vegetables and plants will also be perfectly suitable for your koi fish, and help to create an environment in which they can thrive.

What Else You Should Look Out For?

Maintaining Ideal Conditions

When maintaining your aquaponics system daily, there are certain conditions you’d like to keep an eye on.

Most importantly, you’ll need to regularly check the oxygen, ammonia, carbon dioxide, and nitrate levels of the environment.

Even minute fluctuates could potentially harm the flora and fauna of your aquaponics system.

Checking For Disease

You may need to treat koi fish for disease. It’s important to know the common diseases that your koi can suffer from.

The most common disease is known as ‘ich’, or ‘white spot disease’, which involves bacteria growing in your tank and sticking to the gills of your fish.

There are other diseases you will need to look out for as well, such as tail rot and dropsy.

When treating your diseased koi fish, make sure to first remove your plants, and relocate them to a secure environment.

After treating your koi fish, you will need to carefully change the water in your aquaponics system before returning your plants to their rightful place.

Feeding Cycles

Most koi owners tend to feed their fish once per day.

However, experienced aquaponics enthusiasts have learned that by feeding their fish twice a day, in smaller portions, they were able to produce waste matter containing healthier nutrients, that assisted plant growth.

In this way, you’ll be able to create a self-sustaining environment, where the flora and fauna of your aquaponics system share a unique, symbiotic relationship.

Now That You Know

Raising your very own school of vibrant, healthy koi fish is difficult, time-consuming, and not mention expensive.

However, once you start, it can be incredibly rewarding.

Not only do koi fish look magnificent, but they are also incredibly intelligent creatures, which is why they deserve an environment where they can thrive.

A self-sustaining aquaponics system will allow you to provide your koi fish with the perfect home, where they can grow healthy, and feed themselves.

Not only that, you’ll even be able to grow your own fresh produce, for you and your family to consume.

Now that you know so much more about koi fish and aquaponics, what do you think? Do you already have a functional aquaponics system?

If so, do you intend to introduce koi fish into it? Or perhaps you have koi fish that you’d like to create an aquaponics system for?

Doing so isn’t easy, and we recommend learning how to do it right before you try to create your own aquaponics system.

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