Everything That You Should Know About Koi Fish Breeding

If you have been a koi keeper for quite some time now, you will probably be at the pinnacle of expanding your koi empire.  Or You want to practice koi fish breeding for some dollar bills (….many dollar bills).  How many times have you stood at a vibrant koi shop, and you thought– I already keep koi?  So why don’t I try a hand at koi breeding?  Sure, koi fish breeding is a perfectly viable endeavor for you.  But before you dim the koi pond’s lights in hopes of becoming a koi farmer, having in-depth knowledge about koi fish breeding, and raising koi spawn will help you fare better. 

Where do you find such a comprehensive insight into koi breeding?  Right here!

In this blog, we give you complete knowledge about koi fish breeding with some useful highlights on making the process fruitful.  But first, let us begin with the most important question – should you or should you not breed koi?  What does it take if you do?  And a bonus on which characteristics of koi are possible to breed and which are not.

Why Koi Fish Breeding is Something That I Should Do, or Why I Shouldn’t?

Can’t decide why you should try koi fish breeding?  Well, watching your koi fish giving birth to a koi fry (hatchling) unravels an entirely different facet of the hobby.  You learn about the process and maybe with enough experience, add your insight to further the science of koi fish breeding. 

Consider these advantages of Koi Fish Breeding:

  • It is a DIY way of expanding your koi empire
  • You can make some quick fat bucks 
  • A stimulating process that offers a lot to learn as you research, read and speak with fellow koi hobbyists. 
  • Once you learn the technique of koi fish breeding, you can use them for other fish species.

Consider these disadvantages of Koi Fish Breeding:

  • It’s a time-consuming process
  • It takes a significant monetary investment
  • You will need to expand your space to keep baby koi fishes
  • Your female koi fish might suffer
  • Even though koi fish breeding produces thousands of koi babies. Many die off before the culling process (selective reduction).

Predict the Fish Breed as a Koi Farmer

Predicting the physical characteristics in koi fish breeding is mostly complicated because it is hard to know what recessive genes a Koi is carrying.  This means breeding between a specific pair of koi produces a medley of gene expression in the 5000 plus Koi spawn.  If you are meticulous and maintain snaps or records of the breeding between two koi fish after a year, you could roughly point out the young koi’s parents.  Probability plays a significant role in koi fish breeding.  Be that as it may, some characteristics do come true in koi breeding.  

Here are some of the most common traits that will you in the identification of koi family:

Patterns of Koi Scales

Two normal-scaled koi parents typically produce normal-scaled koi spawns.  While a mirror-scaled pair will produce mirror-scaled offspring.  However, you should keep in mind that koi can carry a recessive gene for some other scale pattern besides the phenotypically apparent one. Taking note of that, it is possible that a leather-scaled koi pair will produce leather-scaled and mirror-scaled baby koi.

The metallic sheen

The metallic sheen is the dominant gene when compared to other sheens in koi fish.  Hence when two koi fish have a metallic sheen and they mate, the offspring will look metallic as well.

Colors in koi fish

Color is the most unpredictable character in koi fish breeding.  You might be successful in breeding a red and white koi – the Kohaku.  But the complexity soars high when you are aiming for characteristics like Heart-Maruten or the zigzag pattern.  The best you can do is make sure that both the koi parents have intense, vibrant colors and contoured shapes.

The unpredictability makes koi fish breeding even more fun.  Every time a koi baby pops out, you can’t help but get curious about what it will look like after a few days.  As a koi farmer, you are always taking on a game of fish roulette.

Preparing for Koi Fish Breeding

Koi fish are very productive when it comes to koi breeding.  The efficiency can be primarily credited to the fact that as a species, koi fish are very comfortable with domestic life.  However, you can’t just put two koi fish together and hope for the koi baby to pop out while you chill.  That might work in some cases, especially in larger ponds.  To become a successful koi farmer, you need top-notch planning skills, the patience of a sage, time, and a whole lot of space.  Only then, koi fish breeding becomes a rewarding venture.  The primary season for koi breeding typically begins in February and lasts until May.

A perfect occasion for reproduction has the following indicators:

  • When the water temperature reaches 68 degrees Fahrenheit.
  • When your koi fish, especially the male koi, seems more energetic or active.
  • When the koi fish begins to feed more.

To be better prepared, start running your breeding tank two weeks prior to the Koi breeding season in your area.

As a newbie koi farmer, you can minimize and control variables by checking off the following:

  • Maintain the health of your koi fish
  • Monitor the breeding site
  • Make sure you have the right tools to change the water
  • You have everything you need to move your adult koi in and out of the breeding site.

The Necessary Tools for Koi Fish Breeding

To help your koi become parents successfully, you need to make sure you are one step ahead with the breeding set up.  In this section, we will help you gather all the essentials to make the breeding process less dubious and flawless.

Breeding tank or pond selection

There are two types of koi fish breeders, those who prefer indoor breeding and those who find koi fish breeding easier in a koi pond.  The location depends mainly on the springtime temperature and the amount of space you can afford.  Because a breeding tank later serves as a nursery, it is preferable to choose an indoor tank.

Show tanks, also known as polyethylene stock tanks, are the best choice for koi fish breeding. Your tank should hold at least 200 gallons of water.  Hence a breeding tank measuring 4 x 4 x 2 feet is ideal.  The sole purpose of getting a tank this big is because after the mating is complete, the population of your koi fish will increase rapidly with the female and male koi and their 2000 or more koi fry. 

Additional Hospital tank

An accessory tank should serve as a hospital for your female koi fish.  Rest is crucial for a female koi after laying her eggs for at least a week or two.  A small stock watering tank will be sufficient for this purpose.

Other essential supplies for Koi Fish Breeding

  • water pumps
  • filter 
  • Air pump
  • Air stones- is essential for better oxygenation.    
  • Tank heater
  • Net for covering 
  • Spawning brushes- replaced plants and serves as a typical spawning ground for koi.

If you are using live branches and twigs, make sure to wash them in soapy water.

Also read – How to Choose the Best Aquarium Heater in 2020

Final Ground for Koi Fish Breeding

Before the overall temperature increases, you must prepare well for the breeding season.  As we have stressed before, koi fish breeding is all about the variables.  It gets even more difficult when you are a newbie koi farmer.  Your Local koi fish breeders are your best guides during the early stages of the breeding process.

Setting up the Koi Breeding Tank

Begin by reducing the water inside of the tank up to a foot.  Then add the Airstones.  This is meant for agitating the water inside of the tank.  Once the water is adequately oxygenated, place the spawning brushes in the tank.  Introduce the female koi fish in the breeding tank.  Let the koi get used to the new environment.

Setting up the Nursery or Hospital Tank

The Hospital tank should be running before your koi fish mate.  Make sure that you keep the water level 6 inches below the edge of the tank.  This will prevent the koi fry from jumping out of the tank.  Similar to the Main koi fish breeding tank, you need to add airstones and a filtration unit.  If the hospital tank is located outdoors, you can simply line it with the koi pond filtration unit.  This ensures that the pH and temperature of the tank are proportional to the requirements.  You can also employ air pumps to facilitate the air stones.

For a better understanding of maintaining the water chemistry in your tank, read – Best Tips For Lowering Nitrate Level in a  Fish Tank

Introducing the Parent Koi for Koi Fish Breeding

In the excitement of initiating your journey as a koi fish breeder, don’t forget to plan for the future needs.  Keeping dated records will help you analyze your methods for a more refined experience.

Moreover, if you are planning to sell baby koi, a detailed record of everything comes in handy should your customers ask for it.

Identifying male and female koi

Each gender has a distinct body shape, making it reasonably easy to tell the sexes apart in koi fish.  Female Koi are more plump than a male, while the latter is rather slender in comparison. Adult female koi fish have tiny pectoral fins.  However, for baby koi, you are at the mercy of subtle clues to tell the gender apart. 

During the breeding season, the male koi fish develops a precise edge on their pectoral fins. The fin of the female fish koi remains unchanged. It is easy to pick the difference by touch. But some koi hobbyist uses their tongue to pick out the difference on the pectoral fins.  You absolutely don’t have to do that.  We are positive on that! 

Choosing the Best Koi Fish for Breeding

For the best koi fish breeding results, you must focus on the color, shape, scales, and fin types of the fish.  The selection of koi fish is made from above.  No, not the divination kind of above. Select the best koi that is the prettiest from the top. 

Number of each Koi by sex

You can select more than one koi male to breed with one female koi.  Most koi fish breeders prefer one female koi with 2 or 3 males, following the theory that competition leads to better breeding results. 

Age of the koi fish

It is essential to choose female koi that are at least three years old.  Certain healthy koi females can breed at two years of age.  Male Koi should be of the same age as the female. 

Female Koi should be in the best of their health to endure the koi fish breeding process.  If you are still unsure, wait until your fish is older.  The practical maximum age for a female koi to breed ranges between 5 to 8 years. 

Choosing male koi of the same age is preferable for mating with the female.  An older male koi is stronger than a younger one, and its better equipped to position over the koi eggs.

Size of the koi fish

Larger female koi are better at tolerating the mating and spawning stages.  Larger fish also lay bigger eggs.  This is especially beneficial because larger eggs have bigger yolks, which means healthier koi fry and abundant nourishment.  Bigger fry has a better chance at survival because it quickly adapts to a commercial diet instead of living off the yolk.

The Right Time for Koi Fish Breeding

Koi fish breeding is mainly dependent on the extension of the springtime, in other words, the Photoperiod.  According to a popular Japanese belief, the moon triggers the female koi to lay eggs.  In line with this belief, Japanese koi fish breeder selects the female koi from the koi pond in the month of January.  They place the fish in the breeding rank for feeding to make it plumper. 

If you are using an indoor breeding tank, make sure that space has a natural photoperiod.  To do this, you can use timers that mimic the extension of the day.  This trick is handy in nudging the female koi to increase the breeding tendency.  The selected male can remain in the pond until the temperature rises a bit. 

The Primary Endeavor of Koi Fish Breeding

The first indicator that your female koi is ready to breed is when it begins to poke around the spawning mat and other egg-laying sites.  She will be continuously followed by the eager male koi, prepared to do its part, and fertilize the eggs.  When you notice such behavior, it is the right time to place your koi in the breeding tank.  Around sunset on the same day, put the male koi in the tank. 

Make sure you cover the breeding tank with a net or mesh.  Allow some time for the fish to remain in the same tank. It might take around 4 hours.  Typically, after the mating process is over, the female koi will lay the eggs at dawn.  You must watch over the process; in case the male koi gets aggressive.  In such a case, remove the original male and replace it with the next candidate.

On the other hand, a male koi fish’s presence is essential in the breeding tank.  It motivates the female koi to explore the spawning brushes.  This is a natural behavior and does not require your intervention. 

Also read – Using Aquarium Plants To Create a Living Artwork

Behavioral Changes during the Koi Breeding season

As the female koi approaches the time to lay the eggs, several behavioral cues align the male and female koi activities.  As the fertilization is external, it is essential for both the koi parents to be on the same page for successful breeding. 

Consider these behavior patterns that indicate the koi fish’s readiness to breed

  • Release of several factors by the female koi that excites the male.
  • Wrestling between the parent koi.  The male pushes the female towards the spawning brushes. 
  • Encouraged by the nudges of the male koi, the female finally lays the eggs.  The eggs are typically coated with a mucous-like coating for adhesion.
  • The male releases the milt or the koi sperms.  The milt appears as a milky haze, and the water current carries it towards the koi eggs.  It then enters each egg via a minute pore called the micropyle.  After the fertilization is complete, the micropyle shuts close. 
  • After several cycles of egg-laying, remove the male koi from the tank if he starts feeding on the eggs.

Parenting the Koi Eggs Until They Hatch

You are through with one milestone after the egg-laying and fertilization is complete.  But this is no time to relax.  The amount of care you offer to the adult koi and their eggs influences how the future koi will turn out as.

The beginning

This is an engrossing time for the koi eggs and you, the proud koi fish breeder.

Here is a list that needs to be checked out on the first day

  • Check the filtration unit in the hospital tank and ensure that the water condition in the tank is optimal for the koi.
  • Once the egg-laying is complete, lift the spawning brush mat and place it in the nursery tank
  • Make sure you check the level of ammonia in the tank where you place the eggs.  Due to the protein of the eggs and the milt, the ammonia levels can go up, if left unregulated.  You can reduce the ammonia level by doing a partial water change or using products such as AmQuel Plus.
  • Place the airstone in the tank to create a gentle water current.  When you place the airstone, make sure you switch off the filtration system.

Since the eggs are still feeding on the yolk, there is no external feed in the tank.  This will generally maintain water quality.  If there is any algae growth in the tank, it is not something you should worry about.  The koi fry will feed on the algae and the microscopic protozoa.

The Process in Between

We have established that the first home for your new koi hatchlings is the breeding tank.  The eggs that turn white are infertile, while the fertile ones remain transparent, and very tiny dots appear on them.  In the first two days, you need to clear the tank of any unfertilized eggs and make sure that airstones are up and running.

After the sixth day has elapsed, you will notice a lot of ¼ inch koi fry wriggling in the tank.  As there is still some residue of the egg yolk left to feed on, you don’t need to feed the koi fry.

If your breeding tank is outdoor, make sure to cover it with netting to prevent birds from preying on the koi fry.

A New Start- the Small Koi Fry or the Baby Koi Fish

This stage of koi fish breeding is the most rewarding one.  Even for new koi fish breeders, it is virtually easy to raise a 3-inch Koi.  As the baby koi’s body colors and recolors, there is nothing more mysterious and delightful for a koi farmer.  Yes, raising baby koi is a big part of the koi fish breeding process, but it is also a tedious task.  Not to mention your expenses will soar up very rapidly.  You will run out of fish food more quickly than ever before (these little finnies are perpetually hungry).

Another critical step is the Culling of almost 99 percent of baby koi.  An excruciating step for koi fish breeder as you form a specific attachment with each baby fish in the pond.  However, no matter how bad you wish to keep every one of them, you will soon realize that it is not practical.  There are around 25,000 fertile koi eggs in your tank. Housing 200 young koi is an arduous task, a real commitment.

Feeding the Koi Fry

Koi fish breeding
Feeding Koi fish with baby milk bottle

You can quickly satisfy hungry adult koi.  On the other hand, specific dietary requirements, and the size of new koi hatchling makes feeding an everyday battleground.  Koi Fish fry feed on their yolk for up to 24 hours after hatching.  Twenty-four hours later, their survival solely depends on you.

Not to mention, there is an exceptionally fine line between feeding the fry sufficiently and tank pollution.  For the first day or two, you can only feed liquid food to the koi fry.  As the growth curve progresses, you can switch to larger solid foods.

Here’s a little table on the types of koi fish food that you will need during Koi Fish Breeding:

Types of koi fish food for koi fish breedingAmount of koi fish food
Koi fry fish feed (liquid)5-6 dozen tubes
Brine shrimp eggs for koi hatchlings14-16 oz (canned)
Frozen Brine shrimp15-18 oz.
Powdered food for koi fry50-51 lb.
Boiled eggsAs required
Koi fish flake food1-1.5 lb.
Powered dry krill16 oz.
Daphnia cubes14- 16 oz
Basic koi floating fish food pellets5 lbs.
Sinking pellets for baby koi5lbs

Koi Fry Feeding Clock

As a general rule of nature, growing koi fry need a lot of food.  But overfeeding will harm them and pollute the tank considering the big koi population in the tank or pond.  Commercial koi foods market balanced nutrition, but it is better to maintain variety in what you feed the koi fry. 

Let’s break down the Koi Feeding pattern into months for simplicity:

The First Month of Feeding

During the first month, you will feed your koi fry at least four times a day.  Liquid koi food is best as it dissolves in water and lasts longer for the koi to feed on.  Monitoring the feeding clock will help to decide on the right amount of feed. Especially for solid koi food.  If there are leftovers after one feeding cycle, you need to cut the amount the next time.  Add a new variety of koi food every time you feed the baby koi.

Here are some tips that will help you fare better in the first month:

  • During the first day of the month, use liquid koi food, one tube for every feeding cycle. 
  • Continue to feed liquid food for three days.  You can increase the amount per feeding.  Baby koi prefer brine shrimp from all other types of koi food. 
  • After the 3rd day, you can add egg yolk slurry, the liquid food and brine shrimp in the feed 
  • On the 8th day, you can add powdered koi fry food
  • After a week of feeding, you can use koi fish food pellets in powdered form.  You can run the pellets in a blender to make powdered koi fish food.
  • After the 2nd week, stop feeding egg yolk slurry to your koi fry.  You can add koi fish flakes or blended krill in the diet.

After one month of feeding nutritious food, your koi fry will grow into an inch-long baby koi. 

The Second Month of Feeding

In the second month, you can continue to feed your Koi four times a day.  Apply the general rule, see how much your koi eats in minutes, and calculate the amount accordingly.  

For a balanced, you can feed your Koi the following food items:

  • Continue feeding Powdered Koi fish food pellets
  • Use frozen shrimp brine instead of fresh shrimp brine.  This is because frozen blocks have adult shrimps which are easier to tear apart and digest for young koi fish.
  • You can use larger sized pellets. You can feed sinking fish food once a day.

After the second month, your koi fish will grow up to 1 or 2 inches long.

The Third Month of Feeding

During the third month, decrease the feeding frequency to three times per day.

 Here are some dietary changes that you can make for your baby koi during the third month:

  • Feed the koi whole baby fish food pellet or powdered adult fish food pellets
  • Cut down on frozen shrimp to half the amount that you fed in the second month.

The protein requirement of baby koi is significantly higher than the adult koi.  Make sure that you purchase koi food with 40 percent protein in it.  If you see whirling or cannibalism in the tank, increase the protein content even further.  Whirling is when your baby koi starts turning in circles in the water, somewhat like a far-gone drunkard.

Since the feed’s protein content is high, make sure to regulate the water chemistry in your tank.  Even when your filtration unit is running, you need to make a partial water change every week.

To Know More About Koi Fish Nutrition Read This Article – Fish Nutrition

The Dreadful Process of Koi Fish Breeding- Culling

You have a colossal population of tiny koi after the eggs hatch.  The number decreases naturally, with some koi fry leaping out the tanks and others getting eaten by their brothers and sisters.  The number of koi fry is still vast and impractical in terms of management.  For the first three months, euthanize unwanted fish fry or find another home for them.  This process of reducing the koi fry population by the koi fish breeder is called culling.

To some, Culling might sound like a harsh step, but reducing the number of koi fish fry helps you with the management.  If you do not cull, you can’t look after so many koi fry which means some may die anyway.  Culling gives your remaining baby koi a better chance at survival.

Which Koi Fry Should You be Culling?

After you baby koi fishes start developing color or patterns on their body, you can cull for the desirable colors.  You can also remove koi fish that are stunted or deformed.  The trick is not to look for beauty in your koi but look at those that have flaws that will hinder their survival.

Here are a few guidelines on culling during the Koi Fish Breeding process:

  • Cull koi that have solid colors.  But keep solid black koi.  They have tremendous potential for growing into Koi Showa.  Showa is a black koi fish with deep red and white markings on their body.  The markings on a Showa koi takes three years to appear.
  • Keep a baby koi that has red spots on its head.  They can grow into a type of koi called the Tancho.  Tancho koi have larger red markings on the head.
  • The pectoral fins should spread out well. If your koi has fanned out fins, keep it. 

How Much Culling is Needed During Koi Fish Breeding?

The goal of Culling is to reduce your mammoth koi fry population to a tiny number.

Here is the month-wise ratio of how much Culling you should consider:

  • 1st month of koi fish breeding – Cull 85 percent of koi fish
  • 2nd month of koi fish breeding – Cull 80 percent of koi fish
  • 3rd month of koi fish breeding – Cull 65 percent of your koi fish

Selective breeding is an essential step for a koi fish breeder.  The primary purpose of Culling is to find the best koi in a vast population and give them a better chance to survive.

FAQs on Koi Fish Breeding

Can koi fish mate with Goldfish? Yes, Koi Fish-Goldfish breeding is possible.  Both Koi and Goldfish are closely related to carp fish species.  The breeding between Koi and Goldfish happens more often in an outdoor koi pond.  A set of two whiskers, larger size, sterility- are some of the exciting features of koi-goldfish spawns.

How to start koi fish breeding? koi fish breeding is a comprehensive process.  You need to prepare the koi breeding station, the standard koi parents, and the right conditions for the koi fish breeding to be successful.  Moreover, your responsibility as a koi fish breeder doesn’t stop once koi fish mate.  You need to prepare for the koi eggs and koi fry for proper nutrition, water chemistry.  There is Culling involved where you control the expansive baby koi population.  Koi breeding is a rewarding endeavor, although a tedious one.

When is the koi fish breeding season? The water temperature and the season matters when it comes to koi fish breeding.  Koi Fish typically only breed when the water temperature reaches 65 degrees to 75 degrees Fahrenheit.  Such conditions usually occur during the Months of may up to June.  Late spring and early summer are the perfect koi fish breeding time.

Do koi fish breed in captivity? Koi fish are perfectly used to life in captivity.  An outdoor pond or an indoor breeding tank is suitable for koi fish breeding.  During spawning, the male koi fish tend to become a little aggressive.  This makes it essential to regulate their behavior and isolate the female koi for healing.

How old do koi have to be to breed? For a successful koi fish breeding, you need to choose female koi that are at least 3 years old.  Choose a male koi around the same age.  This is because koi fish mature entirely at the age of 3 when they are 10 inches long.  The older your koi fish is, the healthier it will be.  This helps in healing faster after the female koi lays eggs.

Can you breed koi fish in a tank? Yes, you can breed koi fish in a tank.  You will need two tanks for indoor koi fish breeding.  One tank serves as the primary breeding tank.  The other tank serves as a nursery or hospital tank where the female koi rests after breeding.  A 200-gallon fish tank will suffice as a breeding station.   

Also read – How to Build Your Own DIY Fish Tank – A Step by Step Guide

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