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Dry Method of Koi Fertilization (Hand-stripping) - Page 2 of 2



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2. Collection of the Male's Sperms. The sperms of the male koi is retrieved through a similar manner of hand stripping, except that the milt is usually collected in a glass beaker. Alternatively, a glass bottle with a large mouth may be used.  Again, wipe the male koi until it is dry before squeezing its belly and letting the milt fall into a glass beaker. Another method for extracting milt is through the use of a plastic syringe, which can conveniently and cleanly suck the milt out of the male koi.  The milt collected by the syringe can then be easily transferred into a glass container.


Dilute the milt with 0.9 NaCl solution at a ratio of 3 parts saline solution for every part of milt.  The same procedures for retrieving the milt can be applied to additional male koi if genes from different male koi are desired for the fertilization of the eggs.


Figure 3.  The milt of a male koi may be retrieved using a plastic syringe and collected in a glass bottle.


3. Mixing of Eggs and Sperms. Once the milt of the male koi have been collected and diluted, the solution can be poured directly into the eggs inside the bowl.   This causes the sperms of the male koi to fertilize the eggs of the female koi. The fertilization can be made more effective by gently mixing the mixture by hand using a large plastic spoon. 


Figure 4.  The milt of the male koi is mixed well with the eggs of the female koi to maximize fertilization.



4. Degumming. Degumming is the process of removing the stickiness of the fertilized eggs.  Koi eggs are by nature sticky to allow them to adhere to surfaces for incubation after natural spawning.  This stickiness needs to be eliminated when the fertilized eggs are to be hatched inside artificial incubators that employ running water. Otherwise, the sticky eggs will form clumps inside such incubators.


Degumming is achieved by rinsing the eggs with three different solutions done in succession.  The first rinse is 4-5 minutes of continuous mixing with a Woynarovich fertilization solution (3 g NaCl, 4 g Urea, 1 L water).  The second rinse is one hour long and uses a modified Woynarovich solution (3 g NaCl, 20 g Urea, 1 L water). This second rinse requires that the eggs be mixed only every 10 minutes, with the rinsing solution being replaced with a fresh one after each mixing.  The third and last rinse, which is done to harden the egg shell,  is just a quick one (a few seconds) with tannic acid solution (1 g tannin, 1 L water) to be followed by a washing with water.


5. Incubation. After degumming, the non-sticky eggs can then be placed in artificial egg incubators without the problem of egg clumping.


A word of caution though - the procedures discussed above require a high level of skill and should not be tried by a novice on expensive koi (or any koi for that matter).  In fact, even expert breeders prefer to let their expensive koi spawn naturally instead of hand-stripping them of their gametes. The article above only presents what the dry method of fertilization is and is not a guide to be followed for an actual operation.   It must be emphasized that improper hand-stripping can cause damage to the koi being stripped.


See also:  Basic Koi Breeding Koi Breeding Considerations





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