A Guide To Breeding Koi And How To Make A Profit

It is common knowledge that koi have been a sought-after commodity for centuries, with individual koi fish selling for hundreds of thousands of dollars. Therefore with so many different varieties of koi and the popularity of koi growing exponentially, a lot of people are wondering how to start a breeding program that is sustainable, profitable, and scalable. 

Breeding koi for profit requires financial investment in a quality breeding pond and a healthy breeding pair with all the popular koi variants’ characteristics. Once a breeding pair has laid its eggs, caring for the koi and identifying buyers is essential.

Breeding koi and making a return on investment requires hard work, trial and error, skills, and financial sacrifice. Therefore, this guide is the ultimate blueprint for beginners looking to breed koi for profit. Let’s explore some of the key points below.

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Which Koi Fish Should You Breed? 

To profit from breeding koi, you need to understand what the koi market wants from koi fish; this is vitally important as the value of koi shifts depending on the koi’s variation and characteristics. 

Generally speaking, buyers want koi with bright colors, uniform colors and patterns, friendly demeanors, and good, healthy genetics. Therefore, you should choose breeding care that you believe can provide uniform, healthy offspring subject to the market’s demands. 

When choosing a breeding pair, you must: 

  • Select a male and female koi. To identify a male koi, look for koi chasing other koi during breeding season or having white growths on their pectoral fins and heads. 
  • Make sure they are fit and healthy (you may need a breeding expert or a vet to give you advice). 
  • Select koi at least three years old, as koi only reach sexual maturity at three years of age. Generally speaking, koi that are ten inches or larger are at least three years old. 
  • Select a breeding pair with colors and patterns that complement/match one another. If you are a new breeder, selecting koi of the same variant is recommended for ease of breeding and the expected outcome. 
  • Make sure to select koi, which are docile and not aggressive. 

When Do Koi Fish Breed? 

Generally speaking, Koi prefer to breed when the temperature increases and the water temperature is approximately 70F. Therefore Koi typically mate during the late spring and early summer months.

Therefore, you should construct a breeding pond during these months and maintain these conditions throughout the breeding, laying, and hatching process.

How To Establish A Breeding Pond 

Although you could put a couple of koi fish in a pond and hope for the best when breeding koi, you should take the time and effort to build a separate breeding pond for koi during the breeding season. 

The benefit of a breeding pond is: 

  • It can be smaller and easier to take care of than a large koi pond, 
  • It reduces the risk of breeding koi, baby koi, and eggs coming into contact with larger aggressive koi, parasites, or diseases, 
  • Depending on the location of the koi pond, you can reduce the risk of koi exposure to predators, 
  • You can closely monitor the diversity of the pond and remove any foreign entities with ease (such as animals that typically cohabitate with koi, such as turtles), 
  • You can adjust the pond specifically to promote breeding and improve the survival rate of baby koi/eggs. 
  • While this may be challenging, establishing a designated breeding pond is a relatively affordable investment that can pay dividends in the future. The most important thing to consider is purchasing quality equipment and consistent maintenance. 

The first piece of equipment you will want to invest in is a specialized koi pond filtration system; However, it may be tempting to buy a generic filtration system or construct your own. However this may prove dangerous to baby koi and eggs if the filtration flow is too strong. 

A filtration system will likely be your most expensive investment, with quality filtration systems ranging between $200 and $2000. Due to the cost of purchasing a filtration system and the need for consistent operation, you should employ the services of a professional to install the filtration system, and you buy a filtration system with a reputable warranty. 

Before installing the filtration system, ensure the pond is free from algae and other large dirt particles. It would be best to manually clean your pond so your filtration system can work at full capacity at installation. 

The second piece of equipment you purchase is a fry mat. The fry mat is a sticky and flat mat that gives koi a safe place to lay their eggs. This creates a space where you can monitor eggs, but it also promotes breeding, as koi will not breed if they don’t believe there is a safe space in their pond to lay their eggs. 

When installing a fry mat, ensure it is firmly secured to the bottom of the pond away from direct sunlight and any currents (such as your filtration system) that may cause the mat to shift or flip over. 

Optional pieces of equipment include: 

  • An aeration system, 
  • Artificial lighting (to mimic the illumination of summer/spring if natural light is limited), 
  • A pond heater (see below for further details.) 

Although a breeding pond doesn’t need to be the size of a regular koi pond (assuming your business model is selling baby koi), it still needs to be large enough to account for the fact that koi lay thousands of eggs during breeding season! 

Finally, it would be best if you avoided the inclusion of unnecessary décor that could release dangerous chemicals into the water, such as copper. While this may not affect adult koi, it may harm baby koi and eggs.

How To Care For Breeding Koi 

The most important feature of keeping koi is building and maintaining a koi pond to their specific needs; this is an expensive endeavor and requires ongoing care and attention: 

  • The water in a koi pond needs to be monitored at an approximate temperature between 60 and 70 degrees. Although this may be cooler than a usual koi pond, it is the perfect temperature for breeding ponds as they promote the incubation of eggs. 
  • If your pond is in a location with low temperatures or harsh winters, you must install a pond heater to maintain this water temperature. 
  • Make sure the water you use in the pond is clean, fresh water free of harmful chemicals and bacteria. You must also ensure that any/all new water that deliberately or accidentally enters the pond (such as rainwater) is safe and clean. 
  • You must install a filtration system that biweekly removes roughly 10% to 30% of the pond’s water. Although this will clear most of the waste, you must also clean the pond manually. 
  • To manually clean your pond, you should invest in a skimmer net. A skimmer net is a scoop tool that allows you to remove debris and pests from your breeding pond safely. 
  • Koi ponds must be 4 to 6 feet deep with approximately 1000 gallons of water per five medium-sized koi. Koi can live for up to 30+ years, koi will grow and breed during this time, and therefore you must ensure you have a big enough pond to prepare for this growth. 
  • Subject to the size and number of koi in a pond, you must install an aeration system to keep the pond’s water sufficiently oxygenated.  
  • Koi are omnivorous. Therefore while koi can live on fish pellets indefinitely, you should vary their diet by providing access to natural vegetation, fresh fruit, fresh vegetables, and protein supplements to promote breeding. 
  • Unlike koi in regular ponds, breeding koi should be fed four times a day for approximately five minutes each feeding time.  
  • Koi are defenseless animals easily stressed by predators and other domesticated animals like dogs and cats. Therefore, you must install your koi pond in a safe area with protection/fencing around the pond to keep predators away from your koi. 
  • Further to the above, outside ponds exposed to bird life should be covered with a retractable net to protect the koi, particularly baby koi. 

How To Tell If Koi Fish Are Breeding?

To initiate koi breeding, you should introduce the female koi to the breeding pond before introducing the male. Adding the female koi before the male is important as it allows the female time to adjust to her new surroundings and establish a suitable space to lay her eggs without the stresses of another koi inhabiting the pond. 

After a few days/weeks, and you are confident the female koi is comfortable and aware of the position of the fry mat, you should introduce the male to the pond and reduce your interactions with the breeding pair so they can grow accustomed to one another. 

When the breeding process occurs, it may appear at face value to be aggressive and hostile; however, the following observations are standard: 

  • Once the conditions are right, the female releases a pheromone to attract and excite the male. 
  • The pheromone causes the male to chase the female to a suitable spawning area. The chase may involve bumping the female and taking small bites, do not be alarmed, as although the female may suffer minor abrasion, this is done to help her release her eggs. 
  • The female koi releases her eggs while the male simultaneously releases his sperm. To identify if this has happened, look for foam or scum on surface of water in breeding pond. 
  • The parents will eat some eggs for nourishment and as a natural act of culling. Do not be alarmed, as some consumption of eggs is unlikely to result in population loss to the millions of eggs laid by the female. 

How To Care For Koi Eggs And Baby Koi

How many koi you want to breed will determine whether you should remove the adult koi from the breeding pond. If you’re going to breed multiple koi, you should place the adult koi back into your main pond or a specialized koi tank. 

A koi tank should be approximately 100 gallons for two adult koi and equipped with essential equipment such as filtration systems, aeration systems, and heaters to keep the water clean and heated. 

If you intend on breeding fewer koi, you can leave the two adult koi in the breeding pond. Just make sure to give them a consistent and varied diet to limit their consumption of eggs and baby koi. 

The removal of the adult koi should happen the moment you witness froth/scum on the pond’s surface, or you identify a nest of eggs, as koi eggs hatch within four days of being laid. 

Before they hatch, there are essential steps you must take to care of the newly laid koi eggs

  • Monitor the pond’s pH levels, temperature, and cleanliness to reduce the risk of harming eggs due to a harsh environment. 
  • A particular concern for newly laid eggs is ammonia levels. If you notice any ammonia level above zero, you should consider a complete water change of the pond or the introduction of ammonia reducing product. When replacing the water, you should opt for a replacement of between 20% and 30% of the total volume of pond water per hour. 
  • Further to the above, a water change may be needed after the mating process as it can result in a foul smell and cloudy water, making it harder for you to monitor the wellbeing of the pond and the newly laid eggs.  
  • When replacing the breeding pond’s water, ensure the eggs remain fully submerged and are not exposed to the outside air. 
  • Remove any unfertilized eggs from the fry pad. To identify unfertilized eggs, remove any white and fuzzy eggs (in comparison, fertilized eggs are clear and often sport black or colored dots, which are the baby koi’s eyes.) 
  • Although it is vital to keep the breeding pond clear before hatching, do not entirely remove all algae from the pond. The reason is that algae is what baby koi eat during their first few days after hatching. 

Once the koi eggs have hatched and the baby koi have emerged, these are the essential steps you must follow to take care of them: 

  • Once hatched, the baby koi can eat algae and other small pond material. 
  • Once baby koi are ten days old, you must begin manually feeding them. You must grind up koi pellets into a fine powder using a grinder, blender, or pestle and mortar to feed baby koi. Sprinkle the crushed koi pellets on the surface of the pound. You must manually feed the baby koi four times daily for approximately five minutes each feeding session. 
  • Although it may take several days for the baby koi to grow accustomed to your presence and learn to eat the koi pellets, remain persistent and feed them consistently. 
  • Once the baby koi have grown in size after four weeks of fine powder feeding, you can increase the size of the pellets you feed them. Although you do not need to crush the pellets into a fine powder, you still need to make the crumbs small enough for the baby koi to eat. 
  • After three months, most baby koi should be approximately three inches long. If you removed the adult koi, you could safely reintroduce them to the pound without any risk of fighting between the adult and baby koi. 

How To Sell Koi Fish For Profit? 

One of the necessary business practices of breeding koi for-profit and recreating natural “survival of the fittest” policies is culling baby koi. Although this may sound like a cruel method of thinning baby koi numbers, there are important reasons for doing so that can be implemented without causing undue suffering: 

  • The reason for culling is that some koi may be born with severe defects that will make their transition into adulthood uncomfortable for the koi. 
  • For healthy koi, culling does not necessitate putting the koi down; instead, you need to remove them from your pond by gifting them to family, friends, and other koi breeders. 
  • Raising thousands of koi is very difficult if you decide not to cull your koi. As a small-scale breeder, taking care of thousands of koi is not ideal in a small pond, and poor conditions can lead to stress and fighting. Not only is this detrimental to the koi, but it can result in a negative return on investment if you cannot sell healthy koi with desirable colors/patterns. 
  • Although it may be tempting to release unwanted koi in the wild, you should not do this under any circumstance. The reason being is domesticated koi do not survive well in the wild, and they can cause serious ecological harm to native ecosystems. 

Before discussing the koi target market, you should be aware of a few things if you are a beginner breeder. 

Firstly because of the wide variety of koi patterns and colors, along with the interbreeding of koi species over multiple generations, it is doubtful that you will breed uniform stock without significant trial and error over many years. 

Furthermore, there is a level of luck to breeding, as pond conditions, diet, weather, stress levels, and the variety seen in hundreds of thousands of koi eggs will inevitably lead to your baby koi growing and developing in a multitude of ways. 

Consequently, new breeders are unlikely to profit significantly when they begin breeding koi because the market for expensive koi will be cornered by breeders that use very advanced breeding techniques to sell premium koi variants to enthusiastic collectors. 

However, this does not mean you cannot make some profit. Instead, a new breeder should accept the reality that they may have to sell large amounts of koi at a meager price until they have developed a breeding pair and technique that produces koi of consistent quality, variety, and health, color, and pattern. 

Therefore, if you want to expand your koi breeding hobby into a scalable and profitable business, you should attend Koi Shows so that you can speak to qualified breeders and learn the advanced techniques of koi breeding. 

Furthermore, koi shows are a fantastic place to meet clientele and understand which variants of koi are desirable and profitable and which koi are not favored by collectors. 

Therefore, although quality, premium koi is sold for as much as $5 000, it is likely that you will have to price your koi at a much lower price for wholesalers, such as $15 a fish. Just make sure to take clear videos and photos and provide ample information about your koi should you choose to advertise your koi business online/via social media.  

In conclusion, although it may be disheartening to spend large amounts of time and money on koi breeding, only to have a small return on investment selling to casual koi owners and pet shops;

 There is ample opportunity to turn a fantastic profit with time and selective breeding.


In conclusion, although breeding koi may appear at face value to be the ultimate “get rich quick” scheme, it requires a lot of time, skill, and financial sacrifice to create a breeding project that can turn a profit into hundreds of thousands of dollars. 

Therefore, you should enter koi breeding with the correct mindset. Namely that breeding koi is a fulfilling and fascinating hobby that, with a lot of work, can scale into a more significant profitable business over many years.





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