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Thread: Estimating Age in Tosai

  1. #1
    Sansai almostgeorgia's Avatar
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    Estimating Age in Tosai

    I have what is probably a pretty basic question for the breeders and more experienced hobbyists with a background in shopping for koi in Japan, but can't seem to find any threads here on Koi-Bito that directly speak to the issue:

    How can a buyer gauge the approximate age of a tosai based on it's length? I realize this is probably a loaded question, if for no other reason than all fish mature/grow at often wildy differing rates, but I'm wondering if there is a 'rule of thumb' that can, none-the-less, be applied.

    As an example, if one is purchasing a 5 or 6 inch tosai at a show here in the States in March, or from an importer of Japanese koi at that same time, can a buyer 'assume' that fish is approximately one year old? And what of a 7 - 10 inch fish purchased at that time? And how does it come that one can purchase 6 inch fish virtually year around from Japan? I thought I understood the vast majority of koi were bred in the early Spring in Japan, though I know they can be spawned for much of the year.

    So, in short form, my question to the experts would be, at say 6, 8, 10 inch intervals and so forth, how many months/years old can one reasonably expect a tosai or even a nisai to be?

    Thanks, in advance for any insights.

  2. #2
    Honmei ricshaw's Avatar
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    Quote Originally Posted by almostgeorgia View Post
    I have what is probably a pretty basic question for the breeders and more experienced hobbyists with a background in shopping for koi in Japan, but can't seem to find any threads here on Koi-Bito that directly speak to the issue:

    How can a buyer gauge the approximate age of a tosai based on it's length? I realize this is probably a loaded question, if for no other reason than all fish mature/grow at often wildy differing rates, but I'm wondering if there is a 'rule of thumb' that can, none-the-less, be applied.

    As an example, if one is purchasing a 5 or 6 inch tosai at a show here in the States in March, or from an importer of Japanese koi at that same time, can a buyer 'assume' that fish is approximately one year old? And what of a 7 - 10 inch fish purchased at that time? And how does it come that one can purchase 6 inch fish virtually year around from Japan? I thought I understood the vast majority of koi were bred in the early Spring in Japan, though I know they can be spawned for much of the year.

    So, in short form, my question to the experts would be, at say 6, 8, 10 inch intervals and so forth, how many months/years old can one reasonably expect a tosai or even a nisai to be?

    Thanks, in advance for any insights.
    Good question. It will be interesting to hear the answer.

    If one is purchasing a 5 - 10 inch Koi at a show here in the States from an importer of Japanese koi, I would assume that fish to be "tosai".

    I expect a "tosai" to be a year or less old.
    Last edited by ricshaw; 06-27-2011 at 04:43 PM. Reason: I expect a "tosai" to be a year or less old.

  3. #3
    Tosai
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    I think that it is very difficult to tell the age of a koi by it's size. 20"+ nisai are not uncommon. I once had a gosai kohaku that was just over 12". Nothing was wrong with it or it's environment, it just didn't grow. I did get multiple chances at Baby Champion with that one...

    Raymond.

  4. #4
    Oyagoi RayJordan's Avatar
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    Lenght is a very poor tool to estimate age. Tosai are baby koi that have lived one growing season. Most but not all tosai will have pec fins that are mostly clear. Also most tosai (baby koi) will have a larger head to body size/lenght ratio vs more mature koi. I once saw a koi that was seven years old and less than 12 inches long. I have seen many tosai that are 12 or more inches long.

    You need to be able to trust your dealer to provide you with the correct age of a koi you are considering buying. Of course you also have to trust the breeder or dealer that sold your dealer the koi to have provided them with the right information as well.
    Disclosure:These opinions are based on my experience and conversations with persons I consider accomplished koi keepers and do not reflect the viewpoint of any organization.

  5. #5
    Daihonmei MikeM's Avatar
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    Ray is on target. If the tosai is from Japan, you can fairly assume it was the product of a May/June spawning. Some late season (July/August) spawnings do occur, particularly in southern Japan. I believe spawnings at other times remain quite rare. Length says more about feeding and stocking rates than the age of a tosai.

  6. #6
    Sansai
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    So does a koi from a July/August spawning stay a tosai the following year because the spawning year isn't counted? I've purchased a koi like this and the dealer was honest enough to explain why it was being sold as a jumbo tosai... but now I never know whether to call it a nisai or sansai now that it has gotten a season older.

  7. #7
    Oyagoi RayJordan's Avatar
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    Quote Originally Posted by Farmer Steve View Post
    So does a koi from a July/August spawning stay a tosai the following year because the spawning year isn't counted? I've purchased a koi like this and the dealer was honest enough to explain why it was being sold as a jumbo tosai... but now I never know whether to call it a nisai or sansai now that it has gotten a season older.
    Think of the Japanese aging system as the number of summers experienced.

    A tosai has experienced one summer. The typical koi is born in May-July and would be called a tosai until the beginning of the next summer when it would be called Nisai until the beginning of the next summer when it would be called Sansai.

    A tosai could be anywhere from several months to perhaps 13 months old depending when it was born. However as soon as the second summer begins it is considered a Nisai. A nisai could be anywhere from 9 months old to 21 months old.

    So the answer to your question is the koi you purchased should have been called a Nisai provided you purchased it the summer after it was born.

  8. #8
    Sansai
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    Quote Originally Posted by RayJordan View Post
    Think of the Japanese aging system as the number of summers experienced.

    A tosai has experienced one summer. The typical koi is born in May-July and would be called a tosai until the beginning of the next summer when it would be called Nisai until the beginning of the next summer when it would be called Sansai.

    A tosai could be anywhere from several months to perhaps 13 months old depending when it was born. However as soon as the second summer begins it is considered a Nisai. A nisai could be anywhere from 9 months old to 21 months old.

    So the answer to your question is the koi you purchased should have been called a Nisai provided you purchased it the summer after it was born.
    So you are saying that it doesn't matter if it is an early or late spawn... it experiences a "summer" even though it misses out on most of the growing season?

  9. #9
    Oyagoi CarolinaGirl's Avatar
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    I don't think it's ever safe to assume anything about the age of koi. I have a couple of fish here that were spawned in the spring, 3 years ago. They are less than 6" in length becuase of where they are living. I have not tried to catch them....but they get very minimal food too. If you saw them, you would assume they were tosai but they are not. I have purchased domestic koi that were way too small for their age, because they were raised in crowded conditions. Siblings to those koi that went into mud ponds were 4 times as large. So I don't think you can ever look at a koi's size and assume it's age.

  10. #10
    Sansai
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    Quote Originally Posted by RayJordan View Post
    Think of the Japanese aging system as the number of summers experienced.

    A tosai has experienced one summer. The typical koi is born in May-July and would be called a tosai until the beginning of the next summer when it would be called Nisai until the beginning of the next summer when it would be called Sansai.
    I thought tosai (regardless of Spring/Fall breeding window) were most accurately referred to as "aka nisai" after New Years Day (Jan 1)?

    -t

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