Aquaponic Koi Pond 101

A Unique Way to Grow Plants with the Help of Koi Fish

Whether you’re a commercial farmer looking for something to branch out into or want to use an existing koi pond and grow something delicious and sustainable, aquaponics is a solution for you. 

Aquaponics uses 80% less water than traditional agriculture, making this type of farming sustainable for the environment.

Aquaponics is the perfect way to produce fresh, organic produce year-round since the fish waste is an excellent fertilizer for growing plants. 

Learn what aquaponics is, how it works, and why you’re absolutely burying an aquaponic koi pond even before finishing reading...maybe.

While I’m not an expert on aquaponics, I am a pond hobbyist and did quite a bit of research on the topic of aquaponics and aquaponic systems for this post. This is my passion, and I love deep diving into how and why certain things in aquaponics work and why they don’t.

In this blog post, you’ll learn:

  • What aquaponics is
  • A brief history of aquaponics
  • The advantages and disadvantages of aquaponics
  • Aquaponic koi ponds and the pros and cons of using koi
  • An aquaponic koi pond setup
  • What you can grow in an aquaponics system
  • Other fish to use instead of koi

What is Aquaponics?

Aquaponics can get broken into two words. “Aqua” from the word aquaculture, which is raising fish in a controlled environment, like a fish farm, and “Ponics,” which is Latin for “to work” and relates to growing things in a soilless medium. 

Plants and fish benefit eachother in an aquaponic system

Aquaponics is growing food through a soilless medium while also putting our fish to work in our soilless growing system. Fish eat algae, which is one of the significant reasons a hydroponics system fails and produces fish waste that is high in nitrogen. This nitrifying bacteria is a great source of fertilizer for the plants.

Aquaponic systems are also a great way to grow plants since they mimic freshwater systems’ natural ecosystem. The symbiotic relationship between water, aquatic life, aquatic plants, bacteria, and nutrients present in this system is how Mother Nature intended it to be, and an aquaponics koi pond is no different.

History of Aquaponics

Much like hydroponics which can be traced back to the hanging gardens of Babylon, aquaponics systems have their roots in ancient Aztec culture. There’s another excuse for us to tell our family why we're so deep into aquaponics.

Modern aquaponics and hydroponics are new industries that are just over 50 years old, unlike the ancient civilizations that birthed these two ways of growing plants.

Aquaponics gained popularity in the 1970s as more and more universities picked up on this unique growing method and refined it to use less and less water. Nowadays, aquaponics, hydroponics, and aeroponics gain more value as drought becomes prevalent in populated areas in the USA.

Benefits of Aquaponics

Whether we plan to grow food for ourselves or turn it into a career; which come on, we all should, there are considerable benefits to an aquaponic system. Not only do we get fresh vegetables without pesticides or weed killers, making them healthier plants, but since we’re growing them without soil, we don’t have to worry about weeds.

  • Naturally organic produce
  • Healthier, more nutritious plants
  • Year-round growing season
  • Sustainable for the environment
  • Reduced water usage from traditional gardening
  • No need to clear out weeds from our garden
  • Faster plant growth
  • Reducing our carbon footprint
  • It makes us more self-sufficient
  • Two incomes, food, and fish, for commercial growers

Disadvantages of Aquaponics

There’s always a downside to every good thing, and sadly aquaponics is no different. 

There is a start-up cost involved with any aquaponic system, not just for the system itself but also for the plants and fish. We also need to keep it well-maintained for optimal growing conditions.

  • High setup costs
  • Not all plants can be grown aquaponically
  • Not all fish can be used in an aquaponic pond
  • It consumes a lot of electricity
  • We need to keep a close eye on plant and fish living conditions

Aquaponic Koi Pond

Koi eat a wide array of plant life, including algae, and their waste is perfect for the plants. However, we need to watch out for too much waste as over-fertilizing our plants can kill them.

Younger koi are better for an aquaponics system as growing fish tend to produce less waste. If we plan to use mature koi, keep an eye on how much waste they’re making and adjust things accordingly, especially when just starting out.

There are several factors when setting up koi aquaponics. We need to know how much room the koi will need, what we plan on feeding them, how they react to the seasons, which can affect plant growth, and how much time we have to devote to the upkeep of our aquaponics system.

Why Koi Are Great for Aquaponic Systems

We won’t need to spend a ton on electricity heating the water in their tank since they can live in water that’s between 55 to 70 degrees Fahrenheit. Koi fish can live up to 35 years, meaning we’ll have friends that last ages.

Koi fish eat algae meaning our tank or pond will be relatively clean. They also aren’t fussy eaters and will eat anything from plant matter to our plants’ extra produce. This means we don’t need to buy special fish food and can save some money.

Koi as part of the aquaponic system

If we already have a decorative koi pond, it’s easy to turn it into an aquaponics system with less hassle than starting from scratch, and we don’t have to spend any money on more koi.

  • Resistant to disease
  • Fewer water temperature changes
  • Improved algae control
  • Long lifespan
  • Can turn koi ponds into an aquaponics koi pond with ease
  • It doesn’t require a special feed. 
  • Tolerant to fluctuations in water quality

Disadvantages of Koi Ponds for Aquaponics

The two main disadvantages for an aquaponic koi pond are the size the koi grow to, and they aren’t typically a food source. 

Mature koi typically tend to be around one to three feet long, meaning a smaller aquaponic system is unsuitable for koi. We should have at least a 200-gallon tank to make sure they live their best lives.

If we plan to eat the fish after they grow, which would be weird after becoming friends for life, but who knows, maybe we will get some grumpy ones. If that’s the case, then koi aren’t the best bet either for a fish farm. 

They have lots of bones, preparing for consumption is a complicated process. What we can do if our aquaponic koi pond gets a bit small for our fish is sell the mature koi to collectors for a reasonable price instead, maybe they will get along.

  • Big fish that grow up to 36 inches requiring at minimum a 200 water gallon tank
  • Typically not used for food sources
  • Expensive to buy with a mature koi costing several thousand dollars

Koi Pond Setup

Here’s what we'll need for our aquaponic pond setup.

  • PVC piping
  • Split pump bypass
  • Grow beds
  • Growth medium
  • Bell Syphon
  • Water tank/aquarium
  • pH balancer
  • pH test strips
  • Koi fish

What we'll build are two separate systems, the koi pond, and the garden. 

First, water from the pond gets pumped through PVC piping into the base of the growth beds where our plants’ roots are. Then the water gets filtered out and back to the fish tank or pond. 

Our plants get held up by a growth medium such as clay pellets, laverock, or river rock. This gives Our plants a stable base as they grow, so they don’t fall over as food gets produced.

We want to ensure that the pH levels are in the ideal range for the koi, which prefer a slightly alkaline range of seven and a half to eight. A neutral pH won’t harm our fish, but anything acidic will cause high-stress levels. Routinely check the water and have a working biofilter or add either a pH up or pH down to ensure that our koi are healthy and happy.

The bell siphon gets used to make sure the water in the growing beds doesn’t rise above a certain level and affects the health of our plants. If something should happen, we’ll need the split pump bypass, like needing to medicate the koi pond water, and we don’t want the water from the fish tank to get into the growth beds.

There are many ways to set up our aquaponics system. We can have the plants placed on top of the pond or hanging over it to just have tubes run across the ground from the tank to the growing beds and back while everything is on the same level. What works best for us will depend on the space available and how pretty we’d like it to look.

Caring for Koi

Koi are easy to take care of when it comes to an aquaponic koi pond. Since they are resistant to disease and easy to please, we won’t need to fuss over rhythm quite so much.

Koi prefer being fed smaller meals several times a day during the summer and as the water cools, eat about one meal a day. During the cooler months, we'll need to keep an eye on nutrient levels in the water to make sure Our plants are still getting optimal nutrients for growing and producing food.

We’ll also need to make sure they’re getting plenty of oxygen, check that pH levels are optimal, and if we can give them some sunlight as this helps improve their health.

What Food Can We Grow in an Aquaponics Pond

When it comes to growing vegetables and fruit in an aquaponics system, some do better than others. Growing vegetables such as potatoes, carrots, or other root plants aren’t great for aquaponics.

Depending on how large our system is will also play a part in what we can grow. Small aquaponics systems can grow:

  • Lettuce
  • Spinach
  • Chard
  • Basil
  • Mint
  • Chives
  • Radish sprouts

If it’s a leafy green vegetable or herb, a small aquaponics pond can handle it with no problem. Larger systems can also grow:

  • Tomatoes
  • Peppers
  • Cucumbers
  • Peas
  • Beans
  • Broccoli
  • Cauliflower
  • Cabbage
  • Blueberries
  • Watermelon
  • Cantaloupe
  • Blackberries

Basically, if it grows above ground, there are ways to plant it in an aquaponics system. Some people have even grown fruit trees in these systems.

Other Fish for Aquaponics

When it comes to aquaponic fish other than koi, there are plenty of species to choose from. 

When we have a smaller aquaponics system, it’s better to have smaller fish. Small fish such as goldfish or tropical fish can be used in aquaponics as well. If we want a growing fish we can harvest for food, tilapia or catfish are great for larger aquaponic systems.

We can’t forget to do our research so we can give our fish the best environment to thrive in, as each species has its own unique needs.

Frank Salvatore

In 2015 our family moved into a house south of Denver, Colorado with a  koi pond.  Since that time I've learned to really enjoy the koi fish and the pond. This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?

About Me

Hey there - I'm Frank Salvatore. In 2015 our family moved into a house south of Denver, Colorado that had a Koi pond. The problem was I knew absolutely NOTHING about koi ponds.

This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?
Learn More About Me

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