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Thread: Inheritance of red eyes in koi and unexpected appearance of many pigmented fish

  1. #1
    Nisai
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    Inheritance of red eyes in koi and unexpected appearance of many pigmented fish

    Recently we obtained some interesting data on inheritance of red eyes in koi. Please see attached PDF file with abstract of presentation which I plan to give at the conference on aquaculture in couple months.

    Here are some explanations and details. It is considered that Akame Kigoi are albino fish with red eyes. However, there are no data on inheritance of albinism inkoi in literature. So, the initial purpose of this study was to investigate inheritance of albinism in koi.

    For production of F1 progeny for this study Laurel Nason, who runs Desert Rainbow Koi Farm in Tucson, Arizona, crossed Akame Kigoi male with Kohaku female inspring 2013. Some fry from the obtained progeny were shipped to Kentucky State University. Later that year we noticed that approximately half of fish from that progeny had red eyes.

    We raised fish from F1 in indoor recirculation systems and ponds during two years and fish reached maturity. In we performed crosses of fish from F1; some crosses from F1 fish with fish from our stock were also performed.

    Theoretically, for determination which allele (controlling either red eyes or black eyes) is dominant and which is recessive, results of crosses F1 fish with the same trait (that is, black eyes x black eyes and red eyes x red eyes) are decisive. Cross of two homozygotes for the recessive allele (aa x aa) will give fish with the parental phenotype only while cross of two heterozygotes (Aa x Aa) will result in the 3:1 theoretical ratio in the progeny.

    So, in crosses black-eyes x black eyes we obtained only black-eyed fish while crosses red-eyed x red-eyed resulted in 3:1 (red-eyed : black-eyed) ratios in F2 progenies. Based on these data it was concluded that the appearance of red eyes in koi is controlled by dominant mutation of one gene. Crosses of F1 fish can be described as:

    Black eyes aa x Black eyes aa >>> 100% Black eyes (aa)

    Red eyes Aa x Red eyes Aa >>> 3 Red eyes (AA + 2Aa) : 1 Black eyes (aa)

    Red eyes Aa x Black eyes >>> 1 Red eyes (Aa) : 1 Black eyes (aa)

    As described in Abstract we also crossed red-eyed female with common carp male with wild-type color. In progeny from this cross all fish had black eyes but about 50% had light (yellowish) body color.

    This abstract was written in summer when we had only data on light and dark lens in larvae and segregations red eyes : black eyes in fry. When fry were 1-1.5-month-old, we noticed that some of them have black pigmentation on body, usually black dorsal stripe or part of it. Recently we investigated segregations among 5-month-old fish in the same progenies from crossing of F1 fish. Percentages of pigmented fish in progenies vary from 30% to 70%. So these ratios 3:1 and 1:1 (red eyes : black eyes) we observed now only among fish with unpigmented body; ratios ‘red eyes : black eyes’ among pigmented fish (having black pigment on the body) were shifted towards black eyes. But yes! - We recorded some fish with black pigment on body and red eyes.

    These data on fish body pigmentation are much unexpected since both red-eyed and black-eyed fish from F1 (Kohaku x Akame Kigoi) do not have black pigmentation on the body. So I suggest now that this pigmentation went from Akame-Kigoi male since before I have not observed that fish without black pigmentation gave pigmented fish in progeny. Apparently genotype of Akame Kigoi is saturated with recessive mutations causing this black (grayish) pigmentation. This is not Bekko or Utsuri types of black pigmentation, something different.

    Hope this information will be interesting for forum users.


    BorG

    Attached Thumbnails Attached Thumbnails Gomelsky et al. Abstract on genetic control of red eyes in koi.pdf  

  2. #2
    Daihonmei MikeM's Avatar
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    Very interesting, and surprising to me. Having black pigment and red eyes completely confuses me.


    Last Spring I was observing a couple of dozen tosai Karashigoi that were very pale, almost white. Some had red eyes. Most had black eyes. And, just a couple had eyes that looked black, but had a reddish gleam when light hit them. The same glint of red was not in the eyes of most with black eyes. It was only a couple. I had not observed that before. I do not know if that relates somehow or not. I did not know what to make of it.

  3. #3
    Nisai
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    Quote Originally Posted by MikeM View Post
    Very interesting, and surprising to me. Having black pigment and red eyes completely confuses me.


    Last Spring I was observing a couple of dozen tosai Karashigoi that were very pale, almost white. Some had red eyes. Most had black eyes. And, just a couple had eyes that looked black, but had a reddish gleam when light hit them. The same glint of red was not in the eyes of most with black eyes. It was only a couple. I had not observed that before. I do not know if that relates somehow or not. I did not know what to make of it.

    There may be confusion if to consider this mutation as an albino one. Since albino mutation blocks completely production of melanin in entire body, in both skin and eyes. But this is not albino but so-called depigmentation or demelanization mutation, which decreases content of melanin in some extent, in both skin and eyes, but not completely. Such type of mutations has been described in fish. I attached picture from article on such mutations in medaka. In this fish about 20 mutations of this type were identified. Usually there is correlation between reduction of melanin content in skin and eyes but degree of reduction varied from mutation to mutation. It is seen on picture that some mutants have lighter body but eyes are black, some have dark-red eyes and skin is little dark; on photo F – real albino mutants with light-red eyes and no melanin on body at all.

    I presume that we have in koi this type of mutation. We have one mutation (not many as shown in medaka) but its expression depends on other genes in fish genotypes which control production of melanin. When we crossed red-eyed koi with wild-type color carp about 50% of fish had light (yellowish) color of body but eyes were black. So, if this mutation would appear, for example, at fish farm where common carp are raised for food, nobody would suggest that this mutation somehow connected with albinism. But in koi, genes controlling melanin production typical for wild-type carp are not functioning (recessive mutations). In this condition this mutation expressed as appearance of dark red eyes in fish. If there will be some other active genes for melanin production in fish genotypes (but not so "strong" as genes of wild-type color) the occurrence of fish with some pigmentation in skin and dark red eyes is possible. We observed that in fish, which have skin pigmentation, red eyes are especially dark – kind of red tint (or gleam). So, different variants are possible since melanin contents in both eyes and skin are variable.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  4. #4
    Daihonmei MikeM's Avatar
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    The 'gleam' of red I saw in the Karashigoi was similar to medaka 'D' in your attachment, perhaps darker, but much like it.

    I have thought of akame as a form of albinism that a koi either exhibited in its phenotype or did not. Having intermediates requires a different understanding. Great stuff, professor.

  5. #5
    Jumbo RobF's Avatar
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    Boris, Thank you for posting your Akame Kigoi abstract for us. I once said that there was no such thing as a koi geneticist, obviously I was wrong, but I know of no other than you!

    Interesting results to be sure. I especially appreciate that you mention a tie to your findings and those similar in medaka (and it is not an octopus).

    Speaking of which I remember that there is someone who crosses kigoi with everything and was often talking about eye color (being dark and whatnot). Maybe some English bloke? I searched the forums that I could and didn't find the stuff though. Anyone know of it?

  6. #6
    Nisai
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    Quote Originally Posted by RobF View Post
    Boris, Thank you for posting your Akame Kigoi abstract for us. I once said that there was no such thing as a koi geneticist, obviously I was wrong, but I know of no other than you!

    Interesting results to be sure. I especially appreciate that you mention a tie to your findings and those similar in medaka (and it is not an octopus).

    Speaking of which I remember that there is someone who crosses kigoi with everything and was often talking about eye color (being dark and whatnot). Maybe some English bloke? I searched the forums that I could and didn't find the stuff though. Anyone know of it?
    Rob, I searched forums too and found interesting post in old (of 2004) thread on Koi-Bito. This is from post #6 from thread Kohaku Fry or Kigoi?

    "... Anyway, it got me paying more attention to kigoi. I'm wanting to know more about the genetics of akame kigoi. The red eyes made me think they were albino types, but I was reading one of those old Japanese mags about albino koi used in some breeding experiments & the author emphasized that akame kigoi are not albino, but simply lacking in part of the melanin-based coloring, not all as in an albino. However, there was no further info on the subject. Seems akame are consistently a purer yellow, but I suspect that is due to being "semi-albino" ... muddy tones are still ready to come out in the genes. ..."

    Who wrote that post? - MikeM

  7. #7
    Daihonmei MikeM's Avatar
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    LOL ... The old Japanese breeders knew things without knowing what they knew.

    I recently came across a half dozen or so Japanese magazines from the 1980s that I did not get around to reading. Maybe there is some tidbit of information lurking in them.

  8. #8
    Nisai
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    Some photos

    Here are several photos as illustration for the first post of this thread:

    Photo 1: Red-eyed fish from F1 progeny (Akame Kigoi male x Kohaku female);

    Photo 2: Larvae with black and light eye lens from progeny obtained by cross of red-eyed fish from F1;

    Photo 3: Solid red fish with red eyes from progeny obtained by cross of red-eyed fish from F1;

    Photo 4 and 5: Red-eyed fish with some black pigmentation on bodies (from progeny obtained by cross of red-eyed fish from F1);

    Photo 6: Pigmented larva with dark eye lens and unpigmented larva with light eye lens from cross red-eyed female from F1 with wild-type color common carp male;

    Photo 7: Juveniles from the same progeny (red-eyed female from F1 x common carp male) with dark (wild-type) and light body colors. All juveniles in this progeny had normal black eyes. Light fish in this progeny have not numerous, mostly contracted melanophores in skin.

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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