Scale -Transparency and Red-Eye Mutations in Koi [CC]


Hello. My name is Boris Gomelsky. I am Professor and Principal Investigator at the Aquaculture Program of Kentucky State University. One area of study on fish genetics which we perform is investigation of inheritance of color traits
in koi. In this short demonstration video I will describe two koi mutations and you will see some koi from experimental
progenies. In this aquarium you can see several transparent-scaled koi. Transparency of scales is caused by absence of light-reflecting pigment guanine. Scale transparency mutations were described
in several fish species. In goldfish fish with transparent scales are
well-known as “matt” color morph. Absence of guanine results also in transparency
of gill covers. Therefore gills become visible. You can see that fish eyes are completely
black. These are so-called “button” eyes. This trait is also typical for matt goldfish. Currently we are investigating inheritance
of this mutation in koi. We are also investigating inheritance of another
trait in koi – red eyes. In this aquarium you see several red-eyed
koi. It is generally considered that red eyes are
typical for albino fish. There is a type of koi called Akame Kigoi that literally means yellow fish with red
eyes. It is generally assumed that Akame Kigoi koi
are albino. First in these studies an Akame Kigoi male was crossed with a white-red Kohaku female with regular black eyes. Some fish in obtained progeny had red eyes while the other had regular black eyes. Then we performed different crosses of fish and revealed based on segregations in progenies that the red-eye trait in koi is controlled not by a recessive but by a dominant mutation. So in this aquarium you see red-eyed koi which
we obtained in crosses. You can see that the eyes are dark red – much darker than red eyes in real albino mutants
in other fish species. In this case the red color of eyes is visible
only at certain light angles. Red eyes are darker because this mutation
is not albino. This is so-called “depigmentation” or “demelanization”
mutation which causes only partial reduction of melanin
content in eyes and skin. Finally, in this aquarium you can see very
unique koi – transparent-scaled fish with red eyes In these fish both mutations which I described
in this video are expressed It is interesting that red eyes in these fish
look lighter. Apparently absence of guanine gives this effect.

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