[an error occurred while processing this directive] Fish Spawning in Koi Ponds

     Spawning in Koi Ponds
  PondStuff! Monthly Pond & Water Gardening Newsletter



By Carolyn Weise

That dreaded word that strikes fear into the hearts of mighty koi keepers!  The rather awful thing that happens the day of your garden party with an aroma that permeates the air for what seems an eternity and ruins the look of a perfect koi pond with globs of mounding unsightly froth.  The extra protein gathers below the waterfall where everyone will be sure to notice.  You shudder as you stare at your formerly (just yesterday!) gorgeous pond and garden.  Your mind races trying to figure where to move the party to or how to clean up that awful mess before guests arrive.  That’s the bad part.  Now the good part:  lovely little babies are coming!  Maybe there will be millions of them.  Maybe you have been waiting for this moment for months.  And maybe you have a long list of people, friends, who want your baby koi.  I hope so.

            Everybody wants to try their hand at raising baby koi.  First we buy small ones to watch grow.  Then we get impatient and buy one or two larger ones for the pond.  Soon, we have a collection of all different size and colored koi. 

            When a koi is three years of age it is ready to spawn.  It doesn’t matter the size as much as the age.  And it is not really possible with any surety to predict the sex of young koi.  Therefore if you have two koi in the pond, the chances of one being a girl and the other a boy are about 50/50.  Add one more koi and the chances have increase by about 50% that at least one is a different sex.  I have never met a koi that was sterile either. 

            The next predictor of a spawn is the water temperature:  72-degrees Fahrenheit.  As the pond water is warming up, the fish are preparing for the big day.  You will see some of the fish starting to get “fat” and then might notice more swimming activity as the day gets nearer.  You can notice two types of fish (males and females primarily), the chasers and the chasees!  The chasers will be the males and the chasees are the females.  As they mature the females grow larger and wider than males, which tend to stay slender. 

            Being egg-layers, koi (and goldfish) will lay their eggs in rocks and plants around the pond.  Actually it is a very rough event and fish can be injured in the process, but most survive.  By mixing large and small sized koi, the smaller ones could be at risk for injury during this spawn.  The eggs and milt are actually squeezed out during the “frenzy” of pushing and shoving against any and all objects available.  Make sure there are no sharp objects in or near the edge of the pond for them to impale themselves upon during the spawn.  A clean mop will do nicely to catch eggs for hatching.  They hatch in a couple of days.  In about four days they begin to swim and will begin to look like little fish.  By this time they won’t be eaten by their parent fish.   Any females that don’t release their eggs will simply reabsorb them for the year.  Not spawning will do no harm to any koi in your pond.  Enjoy!

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