How to Raise Koi in Aquaponics for Profit

In Aquaponic Aquatic by Aquaponic GuruLeave a Comment

In this article, we will discuss the merits of koi and how you could fit them into your aquaponics system.

One of the best parts about having your very own aquaponics system at home is that you can design it to be as pretty or practical as you like and there is hardly a fish alive more beautiful than the koi.

While a fancy setup isn’t entirely necessary, half the fun of raising these cold-tolerant fish is the fact that they look good.

On a more practical level, they produce a ton of waste.

Similar to another member of their family tree, the goldfish, this stunning example of the aquatic kingdom excretes heavy amounts of waste.

Whether you are new to aquaponics or a veteran, learning more about the fish you choose is very important.

Koi are Flexible with Temperatures

When you are first getting into researching aquaponics, koi are not a fish that immediately come to mind.

They’re not readily eaten and are popular as pets than livestock.

But the more you learn about these beautiful creatures, the more they make sense for big-time operations and home growers alike.

They can do well in locations all over the globe because not only do they shine in a variety of water qualities.

Koi thrive in one of the widest ranges of temperatures any fish is capable of managing, period.

They can live in water between 35 and 85 degrees Fahrenheit, though their growth does slow significantly without artificial heat in winter.

This makes them a lower cost option for those who live in cold climates.

Breeding Koi for the Pet Market Can Prove Profitable

If you are an organized individual with a lot of patience and an eye for detail. Breeding koi for the pet trade can prove to be a profitable part of your aquaponics venture.

There is hardly a person alive who does not enjoy a good koi pond.

Selling to pet stores and individuals can be a rewarding way to help offset the costs of feeding your adult fish.

As with any animal you’re looking to breed, make sure you check local and USDA laws for any conditions or certifications with which you would need to comply.

Also, it is also worth noting that, like their wild cousin, the Asian carp, they are illegal to keep in certain areas like Australia and Maine.

So if you’re not even supposed to have them, it stands to reason you won’t be breeding them either.

Koi – High Concentration Waste Producers

Like all of the carp family, koi are bottom feeding, high waste producers.

While that can make keeping them alive long term in a regular tank quite the challenge, it makes them the perfect fertilizer makers for an aquaponics system.

They do best with only a few fish supporting a large grow bed and stock well at 1 pound of fish per 20 gallons of water as they grow.

Adult koi produce an astounding amount of waste and require a minimum of 50 to 100 gallons each to stay in optimum health.

Now, that might seem like a lot for such a hardy fish, and it is, but part of our responsibilities as fish growers is to make sure that the aquatic helpers feeding our gardens stay as happy and healthy as possible.

Plus if you only need a few fish for the same results, that’s fewer fish to feed and less money spent of feeding them.

Koi Grow Slowly

There is no getting around it: koi grow slowly.

It’s a good thing they are not a typically eaten fish because it can take anywhere from 3 to 7 years or more for them to reach full size.

Most will top out at three feet, but with careful management, it is not unheard of for some supersized individuals to reach 5 or even 6 feet in length.

The reason for their mind-numbingly slow growth compared to your typical aquaponics fish is that koi produce an inhibiting growth hormone as part of their waste.

This makes them grow much, much slower than their wild cousins, the Asian carp.

If your tank is on the smaller side, consider adding a biofilter and perhaps doing weekly, partial water changes to help lower the concentration of these hormones in the water.

Pouring the removed water over an unconnected grow bed will give that garden a bit of fertilizer while allowing your fish to grow faster.

Another option is adding chemicals to your water to cancel out the hormones’ effect.

However, this plan is iffy at best, especially since anything you add to the water will be absorbed into your plants.

Many people get into aquaponics rather than hydroponics specifically, so they don’t have to add harsh chemicals to their food supply. Fortunately, this option is often the last resort.

Insulate in Particularly Harsh Climates

Koi are extremely hardy fish who can survive in a wide range of temperatures including those low enough to freeze most other fish.

They are so cold tolerant, in fact, that they’re illegal in some northern states to prevent them from contaminating and invading local waterways.

While that means you’d do best checking your local laws before purchasing your fish.

Also, it means there’s less you have to do to keep your fish going over winter.

A simple, double layer greenhouse can help you make the most out of your growing season.

If you’re only interested in growing plants during summer, all you have to do is keep their water above freezing.

It’s possible to do this without even adding an extra heat source.

The water from fish tanks will help trap and radiate heat even after the sun’s gone down.

Black rocks or plastic instead of gravel over the unplanted ground will help as well.

This can keep your fish and any plants you would like to grow toasty even through the dead of winter.

Keep to Selective Koi Breeding

If you choose to grow and breed these beautiful fish, be sure to take care when selecting your future breeding stock.

The sheen that gives koi their beautiful, almost glowing look can easily be lost in just a few generations without a careful, selective breeding program.

Not only will this make your koi less enjoyable to look at, but it can also significantly lower the profit you’d make off selling their offspring.

Another thing to consider when breeding koi is whether or not you intend to show them.  

It might seem silly to the first timer, but the koi show world is filled with fierce competition.

Some breeders with decades of experience and work put into their fish.

All that effort can really pay off, and a carefully bred koi who does well in the show circuit can be worth thousands of dollars to the right person.

Decoration or Fish for Food?

If you are going to keep koi, you might as well make your set up for them is a pretty one, right?

Digging in-ground ponds not only allows you some flexibility with size and depth, but it helps to insulate the water and looks amazing.

You can even add a few plants in and around said ponds to add an extra bit of flair to your aquaponics system.

Not only will these plants help draw some of the extra waste off your water.

Options like duckweed and water lettuce can even provide a bit of food for these omnivorous fish and can be sourced for free from local ponds.

Plus, it looks amazing, but keep in mind that these plants experience prolific growth and can easily spread to other parts of your system without careful management.

Don’t Overfeed your Koi

Considering the sheer amount of waste that koi produce, overfeeding can significantly harm your growing fish.

A floating pellet may be left partially behind by these bottom feeders and quickly sour in the water.

There are plenty of sinking food options out there at various costs.

Even if the fish actually eat every scrap of whatever you choose to give them, it will still end up back in the water eventually.

Fish poop as much as they’re fed, so ensuring that you’re only feeding between 2 to 3 percent of their body weight per day is especially important for koi.

In closing, koi are a beautiful fish with an unmatched tolerance for cold temperatures and the ability to survive in waters other fish would find too polluted.

They are the perfect choice for a mild climate, and a selective breeding operation can add a little cash through the pet trade to offset the costs you lose from not processing your stock for food.

They are incredible fertilizers, and a smaller number of fish can support a much higher plant concentration than most other species.

They eat pretty much anything and are fun and exciting to watch.

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