You are here: Home > Koi and Pond Article Library > Breeding Koi

Breeding Koi Fish

Breeding Koi page has a lot of valuable information. You may want to bookmark this page or print it out to have as a handy reference as you will use it often.

Breeding Koi and taking care of your Baby Koi can be an exciting process, watching nature at work, but it can be a hard job to do. Especially if you do not have a lot of time to watch your Koi. As you well know (if you already have Koi) they are full of surprises, and the same goes true for breeding Koi. Having given birth to a new generation, they would as willingly eat it as see it grow up. This attitude will continue until the baby Koi are maybe 3 in (8 cm) or larger in total length.

Correct nutrition makes a major contribution to the vitality and color of a fish, so supplement the normal diet of your Koi (while in the spawning tank) with good quality frozen foods, such as bloodworms and daphnia. Feeding these prepared foods will made up for any live foods that the fish are not eating wile they are in the spawing tank.

Breeding Tips

Koi keepers who are committed to breeding should take the following to heart:

• Select Koi parents with the best attributes of their variety. Pretty Koi parents do not necessarily make pretty babies, so choose parent fish on the strength of their body shapes, good quality color, and good scalation rather than looks alone.

• Do not use show quality koi for breeding; they will suffer bruises, cuts, torn fins, and missing scales, as well as stress during spawning.

• Get both parent fish into prime health before spawning and again afterward.

• Cull the fry. Few varieties breed true, and every poor specimen must be weeded out in order to strengthen, not weaken, the gene pool.

• Don’t make errors. An entire breeding can be wiped out through carelessness and oversight.

• Keep notes and records for future attempts. Above all, do not expect a breeding to produce multiple champions.

Spawning Koi

Even after careful planning, male and female Koi will sometimes swim around enjoying the company and not do anything until days later, when suddenly you least expect it they will have exhausted all their passion and, by the time you find out they will have already dined at leisure on their own eggs.

After the initial risk-stage (3in in length) has passed then Koi are extremely friendly with their baby Koi and any other fishes and they will not harm them.

The female will send out pheromones (a scent) which will drive the males nuts and finish the maturity of its sperm and the male will then chase the female. They can be seen constantly nudging the female. It may look like one Koi is being bullied by another Koi. This is quite a brutal affair because unlike most fish the gravid female koi cannot lay eggs they have to be driven out of her by a male.

Fish will come into spawning condition at the end of June or the beginning of July, depending on the water temperature. Mating activity usually happens whenever the water heats up rapidly and is more apt to happen in the morning and evening hours.

Spawning (breeding Koi) will generally last only 20 to 30 minutes and can easily be missed. A good indicator that spawning has happened is to look for the presence of a froth or scum on the water’s surface.

Keep checking for translucent eggs, so they will not be eaten. Male Koi will be ready to breed when they are 2 years old, but females should be 3 years old. It is possible though that younger Koi will breed but their offspring will be of poor quality.

Eggs are spawn and sperm is milt.

The female is capable of carrying around 100,000 eggs for every 1kg of body weight. So a female of 10kg in weight will pass 1,000,000 eggs of which 60% will hatch.

Dependent on temperature, the egg will hatch in around 5/6 days but the poor little fry has not really had time to develop, but the longer it stayed in the egg the bigger the chance of being eaten, so mother nature again has equipped the newly emerged fry with only the bare essential but everything the fry needs to survive the next few days while further development takes place.

Koi and Gold fish will generally spawn just after or during an isolated warm spell as spawning time becomes imminent, you will notice the males chasing the females around the pond. This activity will get progressively more in earnest as the days go by and spawning gets closer.

Goldfish mate and produce young earlier than Koi. A Koi must be about 3 years old before he or she can produce offspring. Goldfish are the "hussies" of the pond and are always "going at it" no matter how old they are or what time of year it is. Koi, on the other hand, are more selective about the times and generally spawn only once or twice a year and it is during times of water temperature change or a heavy rain. It's not unusual for a group of Koi to spawn during a Koi show after being transported from their home pond and put into show tanks.

Sexing your Koi

Sexing Koi is difficult if they are not in breeding condition and more so when they are young. As the males come into condition, they develop little white spots, called tubercles, on their pectoral fins. Do not confuse them with white spot which is an ailment. The tubercles will be seen about March and subsequently, depending on how warm the water is.

The breeding Koi female will start to swell in the midriff area and the swelling will tend to be one sided, this is the developing eggs in her ovaries. Your female will regularly feed more eagerly than males.

The opercula (the bony covering to the gill chamber) and head on the males become quite rough, like sandpaper. Male fish usually feel rough to the touch on their opercula (the bony covering to the gill chamber) and head, they can also have a slightly yellow tinge to the white skin on the head. You can run your hands gently over the cheeks and sides of the Koi and if it is male they will often feel rough to the touch, rather like sandpaper, and if it is female they will feel completely smooth. The roughness is caused by tubercles which grow along the sides of male Koi and which they use to stimulate the female fish to release her eggs when spawning.

Another way to sex your Koi: Female Koi have a line running from head to tail which has another line running across it at the tail end. Male Koi do not have this cross-piece. Instead, they just have a simple line running from head to tail. However, this difference is not easy for a non-expert to distinguish, you need a very experienced eye to do this accurately.

If you have Koi and Golfish in your pond they will mate. Do Goldfish and Koi Interbreed? The answer is yes but the offspring are not what you would call quality. In fact, they are not the prettiest of fish and thank goodness they are sterile.

Spawning Tank

If you plan on Breeding Koi Carp you will need a spawning tank. A spawning tank can be any container that has dimensions of about 8x6 ft (2.4 x 1.8m) surface area and a depth of not less than 12in (30cm). Obviously if you plan to run a couple of females with perhaps 5-7 males then you will need a much bigger tank-in fact you will need a breeding pool, but this would be a bigger operation than the average beginner would contemplate. Make sure and put a spawning medium for the eggs to fall into. This could be any hardy aquatic plants, bristle brushes, or you can purchase spawning mops from your local dealer. Branches of conifers (evergreen tree or shrub) are also used and Spanish moss is a favorite choice for many koi breeders.

The medium is used purely to give the eggs something to stick on. Cover about two-thirds of the tank with the medium. After the Koi fish are placed in the tank the male will chase the female and bump her rear end to encourage her to shed her eggs for the Koi breeding to take place. The male will then release his sperm (known as Milt) it contains millions of sperm, only one sperm can enter one egg. This will normally happen in the early morning. Try to avoid disturbing the Koi breeding before and during spawning, but keep a careful eye on them, as the males may bully some females. If this happens, remove the female and place her in a separate pond.

When they have finished spawning, the females hang head down, respiring heavily, and the other fish will become less excited. Gently remove the spawning medium and carefully place them in a vat for incubation.

Baby Koi

Once the spawning and Koi breeding (fertilization) has taken place, the parents must be removed otherwise they will eat the eggs. Koi eggs will usually hatch within 4-7 days depending on the temperature, the warmer it is, the quicker the hatching. The recommended temperature should be 68-77° F. The eggs do not hatch all together, and some may fail to hatch at all. Once the eggs hatch the baby Koi are able to live by absorbing their yolk sac, they will not need to eat for 2-3 days.

The spawning tank can be the rearing tank as well in the first weeks of the fry’s (baby Koi) life, just make sure and remove the parents.

When the fry have hatched, they will instinctively seek shelter and hide in any cover they can find. This is what the spawning medium is for. Using a special sticky pad on their heads, the fry attach themselves to the spawning medium, or to the vat wall. At this stage in their development, the young Koi have no swim bladder, mouth or vent. They breathe by absorbing oxygen through the fine blood capillaries that surround the yolk sac, which is still attached to the gut. It is essential that there is plenty of oxygen entering the water at this stage, as a reduction in the quantity of dissolved oxygen in the incubator could lead to mass mortality.

The Koi fry have only one fin, which encircles the posterior end of the body. As the Koi grow, feeding on their yolk sac until all the yolk is utilized, they develop paired fins, a mouth and other organs. After two or three days, the young Koi swim up to the surface and take two or three gulps of air, which they force into their swim bladder. They then start to swim freely in mid water, usually gathering around the air stones, a sign that they are ready to be fed.

For the next 3-4 weeks they should be fed liquid or powdered fry food.

It is very important that the rearing tank be clean as well oxygenated. After one month from hatching you may feed your baby Koi. How often do you feed baby Koi you may ask? The answer is frequently. Egg yolk is favored by many breeders. The main thing when feeding your fry is that the food be small, of high protein content and is fed many times a day. Remember, make sure and keep the water as clean as possible. Koi fry at the 'swim up' stage do not have any developed taste buds and so must detect their food by sight. Therefore they need to have food all around them.

Hard-boiled egg yolk is an ideal food for the first day or so - this has very little dietary value, but will increase the size of the stomach. Newly hatched brine shrimp (Artemia sauna) larvae are also a good food source for young Koi fry. Start feeding the brine shrimp when the Koi are about one week old. After another week or so, the baby Koi will be ready for a mash diet(the powder dust that is left after the manufacturing process of fish food). From this time onwards, feed the koi food of a size that can be taken by the smallest fish in the vat.

You will need to remove accumulated debris and waste frequently during this first feeding stage. A siphon made from aeration tubing is ideal for removing settled and suspended waste from the incubator, and an old toothbrush is useful to clean the outlet screen. You should also add fresh water regularly to the vat to remove nitrates and ammonia. Tap water which contains high concentrations of chlorine, should be aerated before it is added to the vat, to allow the chlorine to evaporate. After three or four weeks, the baby Koi will have grown to 5-l0mm(0.2-0.4in) in length and will be starting to take larger quantities of more generously sized foods.

You are here: Home > Koi and Pond Article Library > Breeding Koi

Keep Current With The Koi Pond Blog | Click Here to Return to Build a Koi Pond Homepage | Click Here to See Our Koi For Sale | Click Here for Quality Algae Products | Click Here for Container Water Garden | Nishikigoi Terms & Koi Glossary