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Thread: sex of koi

  1. #1
    Sansai
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    sex of koi

    I wonder how to see sex of koi from bottom? I ready try by catch all my fish and looking but all is look same to me? anyones have a picture or draw a simple picture how different between female and male? thank you

  2. #2
    Daihonmei PapaBear's Avatar
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    Quote Originally Posted by nguyen4 View Post
    I wonder how to see sex of koi from bottom? I ready try by catch all my fish and looking but all is look same to me? anyones have a picture or draw a simple picture how different between female and male? thank you
    I'm lousy at it myself, but age makes a huge difference in being able to tell.
    Mature females tend to be thicker built than the males, especially after winter. Female vents tend to be a bit puffier than males, but that isn't universally true. Neither is fin shape, but some people are pretty good at guessing on young fish just by the fins... Not me The easiest way for me to tell is the obvious eggy shape on spring females, and the rough gills on males during the spawning season.

  3. #3
    Sansai
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    my fish just 12"

  4. #4
    Oyagoi bekko's Avatar
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    Female vent roundish or oval and slightly protruding. Male vent more triangular and concave.

    -steveh opk

  5. #5
    Tategoi The Pond Digger's Avatar
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    Sexing by the vent?

    At what size would you say sexing koi by inspection of the vent is accurate? Tosai or bigger? If that is the case, do koi breeders use this technique when making their final selections before making the cut? Toss them back in the mud for one more season or to sell them?

    I have no doubt, the vent inspection of thousands of tosai would be a laborious task, so not a common practice. However, I can also see the value and importance of determining the sex of koi at a very young age to a breeder when making a final decision to keep or sell.

    Interesting...........

    The Pond Digger
    "Doubt sees the obstacles, Faith sees the way!"

  6. #6
    Honmei KoiCop's Avatar
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    Hello nguyen4 . . .

    Like I posted to dg in her thread, there are many, many threads here on K-B with detailed discussions on sexing koi.

    You can always use the search function to find a couple of the most recent ones, and then ask followup questions. This is a complex issue and lots of study will be required to master it.

    For starters, here's one on sexing koi:

    http://www.koi-bito.com/forum/general-koi-forum/6495-future-koi.html

    pd . . .

    Checking the vent is a critical part of the labor intensive culling (sembetsu) process.

    And since a female is worth roughly 3 times what a male is (a convenient rule of thumb for equal quality fish), failure to properly sex tosai at the 80%+ level while culling can mean the difference between the farm having a successful harvest and a losing one.
    Don Chandler
    Member: AKCA, ZNA, KoiUSA

  7. #7
    Daihonmei aquitori's Avatar
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    I say the best way of checking any fish is in early to late spring when the water is a bit warmer. There is away of checking the fish by checking/feeling the pecs and gill plates by examining the fish out of the water and checking for the sunken tiny pits if the water is still cold(in good lighting and angle you can see these tiny pits). Males will have these tiny sunken pits as females wont. These pits will later rise if they are males.

  8. #8
    Sansai
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    Last night i saw a thread on other board with picture about how to look at vent but not clear. I think i will wait few more month and check it again

  9. #9
    Oyagoi bekko's Avatar
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    If you wait until spring it gets much easier. Tubercles as Tony suggests or by stroking the abdomen to see if it has milt. Short of seeing eggs or milt, there is no single characteristic which is fool-proof. Here is an article:
    http://www.raingarden.us/sexingkoiandgoldfish.pdf

    -steveh opk

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