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Thread: Genetic Predisposition to Shimis in Kohaku

  1. #1
    Honmei
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    Genetic Predisposition to Shimis in Kohaku

    I was asked an interesting question the other day that made me think. Would koi "bred" in soft water be more likely to acquire shimis once they got to an owner's harder water?

    Let me first say that I didn't have a clue but that I started thinking on it a bit.

    Of course the question is much more complex than what it would first appear. Shimis are the results of a ressesive gene that has not yet been bred totally out of a line (I would think). This is why I believe some Kohaku breeeders have more susceptibility to shimis than others. As such they would be a genetic flaw for Kohaku. Now, if the breeder was in an area with soft water I would think logically that the ressesive gene may never visualize in the form of a shimi at least to the point where what hardness there is would help to bring it out? Thus, logic would seem to dictate that any advanced culling (or selection of Oyagoi) would only take into account shimis that appear up to a specific level of hardness? Kohaku breeders with harder water would logically sellect oyagoi without shimi even in their harder water and thus their koi "may" be less prone to shimis overall?

    OK JR, what say you?
    The views presented are my personal views and not that of any organization that I may belong to unless otherwise specified. [email protected]
    CKHPA

  2. #2
    Daihonmei PapaBear's Avatar
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    Not JR, but I'd like to toss out a little food for thought to go along with your query.

    A number of years ago there was a good article on Barstow Koi out in Cali. As I recall your thoughts were very much reflected in their breeding operation as the natural hardness of their water appeared to produce Koi that were more "genetically fit" for hard "American Water". It would be interesting to hear from them about their observations.

  3. #3
    Sansai
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    Quote Originally Posted by schildkoi View Post
    ...Kohaku breeders with harder water would logically sellect oyagoi without shimi...
    As a first pass, I'd question how much of a role shimis really play in oyagoi selection?

    Would a breeder really pass up a big beautiful female with great shiroji and excellent conformation because of a few shimis? Or skip over a big bodied male with perfect persimmon hi?

    At some point, particularly with a species with such extreme heterozygosity, it seems that any selection pressure for a somewhat transient trait would be marginal.

    -t

  4. #4
    Oyagoi RayJordan's Avatar
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    I certainly do not know the answers about shimi's but I also think it is much more complicated than just hard and soft water. Genetics certainly play a role as has already been stated.

    When I have asked several Japanese breeders about shimi's they all indicated that they would love to eliminate them but they thought it was impossible. Even the very best top quality koi all get shimi's if they live long enough. Also several felt crystal clear water and intense sunlight increased shimi's. Also there are different kinds of shimi's some sit on top of the skin/scale and are very easy to remove while others occur from deeper in the skin and this makes removal much more difficult without leaving an apparent scar.

    Just as we tend to get age spots, freckles, moles, etc. as we age perhaps something similar happens naturally with koi.

    Another interesting issue with no known prevention is hikui.

    If a breeder could develop a shimi and hikui free koi the world wold beat a path to his door. Wait a minute perhaps they exist already we call them carp.
    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
    Jumbo RobF's Avatar
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    The problem with discussing shimis is that nobody knows what they are! Other than small black spots that appear associated with the red on kohaku? Does someone have a better definition? Microscope slides showing cross sections? In other discussions I have pointed out that studies of the reaction of carp skin to acid and copper and cadmium describe one of the responses as the intrusion of melanosomes into the epidermis. Perhaps a shimi is such a response. A genetic predisposition is of course possible, and potentially demonstrable, but as far as I know this remains anecdotal. A “shimi gene” per se as an explanation right now would seem a bit speculative. My familiarity with the literature on the subject is admittedly limited, but do we even know what the black chemical in a shimi even is? Yes one would think it is melanin, but if so, where did this melanin come from? From the red pigment cells?

  6. #6
    Oyagoi Flounder's Avatar
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    Quote Originally Posted by RayJordan View Post
    I certainly do not know the answers about shimi's but I also think it is much more complicated than just hard and soft water. Genetics certainly play a role as has already been stated.

    I agree Ray, I have sister koi of the same age and another 1 year older but it seems like the best is the one that would get shimmi.

  7. #7
    Oyagoi
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    i have had a koi with shimi in white area also so for me does not effect only red area.
    one koi had it in both the white and red area just little flecks.

  8. #8
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by RobF View Post
    The problem with discussing shimis is that nobody knows what they are! Other than small black spots that appear associated with the red on kohaku? Does someone have a better definition? Microscope slides showing cross sections? In other discussions I have pointed out that studies of the reaction of carp skin to acid and copper and cadmium describe one of the responses as the intrusion of melanosomes into the epidermis. Perhaps a shimi is such a response. A genetic predisposition is of course possible, and potentially demonstrable, but as far as I know this remains anecdotal. A “shimi gene” per se as an explanation right now would seem a bit speculative. My familiarity with the literature on the subject is admittedly limited, but do we even know what the black chemical in a shimi even is? Yes one would think it is melanin, but if so, where did this melanin come from? From the red pigment cells?
    Exactly, Rob. Like so many things concerning koi, we just have a label for a visible trait. What we call shimmies could come from multiple different causes/interactions. We only have anecdotal evidence. The contrariness of experiences makes me think there are likely more than one cause affecting individual fish differently. Certainly there is some genetic reason, and some environmental reason, but not necessarily the same ones in each instance.

    I concur with Steve's thinking in the initial post. I have one Japanese bred Kohaku that has never had shimmies. Every other Japanese-bred Kohaku I've owned has gotten shimmies. I have not gotten shimmies on any domestic-bred Kohaku. My experience is no basis for making a broad general statement, but it sure causes me to hesitate when considering whether to spend the koi budget on a Kohaku.

  9. #9
    Daihonmei
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    Hi Steve,

    The appearance of sumi appearing in kohaku has several explanations. And if you examine shimmy closely, you will see that what are called shimmies come in very different looks, locations within the skin layers and locations on the body.
    All these things hint at what the sumi is.

    To complicate things, shimmies need to assessed also in context to what grade of koi you are looking at.

    So to begin at the beginning koi of a low grade typically have wild type sink, and in this example atavism. This is a simple reversion back to wild type genes (wild carp have peppering of black cells for camouflage) and it is this example that the old Japanese explanation of water conditions fundamentally arises from. But this example, although still possible as an explanation in individual case, is becoming less and less the driver for shimmies in modern nishikigoi.

    The second example or condition is the crossing of sanke with showa. The offspring can look phenotypically like either kohaku or sanke but a percentage will carry sanke genes genetically. I would like to add here that sumi in nishikigoi is not the same as sumi in wild carp. The reason being, the best sumi is a mutation based in hypermelanism.
    I sent a long time and many posts on the gene link from blue eye shadow, silver fern pupil and shimmies beginning some ten years ago now. That was early recognition of what are called linked traits demonstrated in phenotype and are expected gene expressions. In this example we used to see ‘ pure’ kohaku ( black doll eye and shiro eye brow). Now we see kohaku with make linked phenotype eye and eye lid and sometimes later, sanke markings ( albeit it weak) this leads us to the third example

    The last example is also linked to both example one and two and that is the example of mutation dominance.
    ALL nishikigoi are living examples of mutation genetics and typically are recessive genes in nature. But there is the same hierarchy of gene domination and combination within the recessive gene pool. So we have dominate recessives and also dilutes. In this case, the back crosses back to fish caring other sumi traits can emerge in gene combinations. This is also seen in the ‘new goshiki; by the way and has always been present in the gene pool of the a goromo variety.

    Big subject. JR

  10. #10
    Daihonmei PapaBear's Avatar
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    Big subject for a certainty, but Steve's original question does provoke some opportunity for thoughtful discussion on the relationship between water hardness and shimmie presence.

    The notion that Shimmies are a genetic flaw is easy enough to accept as it is only logical. A layer of refinement that simply hasn't been perfected in the Oyagoi. I seriously doubt that DNA would be altered by the relative hardness of the water in any direct manner so for the sake of this discussion we can set that aside.

    The consideration that prospective Oyagoi living in hard water may be more prone to display shimmies IF they possess that genetic weakness has some legs. By extension, if prospective Oyagoi living in that same hard water do NOT display shimmies it seems reasonable to expect a higher level of genetic refinement on that singular issue and their offspring would logically be less prone to develop them.

    To me it only seems reasonable that "hardening" the prospective Oyagoi in water to weed out that trait during the parent selection process could potentially yield good results in the offspring.
    Larry Iles
    Oklahoma

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