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Maintaining a Koi Brood Stock



A group of mature koi used for breeding and propagating new koi is known as a 'brood stock'.  Not every koi hobbyist maintains his or her own brood stock.  However, those in the business of selling koi (especially commercial farms) can not do without one.  This article discusses what people in the koi business do to maintain a viable brood stock.



Having a reliable and viable brood stock is the foundation of any koi production business.  Without it, a koi production business will not have a steady supply of millions of koi fry from which to select the genuinely sellable koi.  For a koi business to have a good reputation, it must only sell good koi, and we all know that not all koi fry will grow to be 'pond-worthy.'  It is for this reason that a large percentage of every generation of koi fry born must be culled - so that only the best koi will grown and sold to solidify the reputation of the business. Thus, a business must produce much more koi fry than it intends to sell every month.


So how many koi must your brood stock have?  Well, it depends on how much koi fry you want to sell every month. Let's do the math.  According to experts, it is fair to assume that only 7% of koi fry born will have a marketing potential.  Thus, you can only sell 7% of the koi fry you successfully hatch -  all others are presumably not good enough to sell and should be culled. 


Koi produce about 100,000 eggs per kilogram of weight.  Now, assuming that each of your female koi is medium-sized and weighs 2 kgs., then each of them can produce 200,000 fry every spawning.  Thus, you can expect to get 14,000 koi fry to try to grow and sell for every female that successfully spawns.


This means that a small brood stock consisting of 3 medium-sized females and 3 medium-sized males can give you 42,000 baby koi every year, assuming that each female is made to undergo just a single spawning annually. This is a conservative number for an annual production since in reality, efficient koi farming methods and multiple spawning cycles will allow a koi enterprise to produce 3 million koi fry a year with just 70 pairs of koi.  By the way, experts say that one has to take into account the fact that 25% of the brood stock needs to be replaced every year due to unforeseen losses for various reasons.


Your koi brood stock must consist only of mature (2 to 4 years old) and healthy koi with absolutely no deformities.  Brood stock koi must also possess all the best qualities of a koi, from perfect body conformation to high-quality colors and well-distributed patterns.  Excellent koi will still produce unacceptable fry, but there's a higher chance of getting great koi from great parents.  This is why koi show champions command extremely high prices.


Once you've selected and acquired your initial brood stock, you can just add more as needed and replace those that are lost or become unfit for breeding.  The important thing is to keep your entire brood stock healthy and fecund at all times. 



Koi can spawn naturally twice a year, with the first spawning usually being more productive than the second one.  The second spawning is also referred to as the 'late spawning'. Since temperature plays an important role in koi reproduction, the time of the year during which they spawn may differ from country to country.  In tropical and subtropical countries, the first spawning of koi usually occurs during the months of March or April while the second one usually occurs in the months of July or August.   Isolation of the spawners in preparation for actual spawning must therefore be done in February and June for the first and second spawnings, respectively.  To read more about the basic method for koi breeding, see Basic Koi Breeding.


After every spawning activity, the spawners must be returned to the main pond where they are maintained until it's time again to isolate them for spawning.


Koi brood stock must be properly fed in order to stay healthy and prolific.  They must be provided with a balanced diet that includes various nutrients and vitamins on top of protein.  The food must make the koi healthy but not obese, since obesity is also bad for koi.  Complementing koi pellets with natural foods is recommended.  Koi that have just undergone spawning are exhausted (and possibly injured), and will therefore benefit the most from proper nutrition which will aid in their fast recovery.


See also:  Koi Breeding ConsiderationsBasic Koi Breeding






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