Kohaku(turned Kosui) Breeding Project 2025

[Coldspringsfarm]

I did a cull on the Kosui today, except practically all of the fish appeared to be Kohaku like. I found exactly 2 fish that were scaleless. One of those almost assuredly came from the Shusui spawn. Not sure how it ended up in the swimming pool.(Pics below) I culled around 300 fry and kept 130. I didn't get all of the fish out of the pool but they started getting wise to my netting and making it difficult. I am pretty pleased with the keepers. At this point, it's like the Shusui male had almost no influence on the appearance. I did keep 5 or 10 fish that had slight dark spots on their head, but the pattern was still Kohaku like, including being fully scaled. I feel like the red pattern might be more laterally oriented on some of the fish, but it's really hard to tell at this juncture.

Shusui Odd Ball



All Keepers



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[Coldspringsfarm]

Here is a short video of my favorite patterned fish thus far:
https://youtu.be/S4cpQ0Xjd5c?si=CfxInLAzEd-AXvKd



And this is a scan through the entire batch of keepers:
https://youtu.be/Om2Q_5NRGPs?si=A1_Qc1ODcfgFEnQv


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[Matt24]

I did a cull on the Kosui today, except practically all of the fish appeared to be Kohaku like. I found exactly 2 fish that were scaleless. One of those almost assuredly came from the Shusui spawn. Not sure how it ended up in the swimming pool.(Pics below) I culled around 300 fry and kept 130. ... it's like the Shusui male had almost no influence on the appearance. ...

In another thread you mentioned ...

... in my Kosui/Kohaku spawn, the Shusui male traits must have been recessive because essentially all fry are scaled with Kohaku patterns. ...

I don't know much about how Kohaku and Shusui patterns interact. However, I thought the science and research of scalation (fully scaled, scattered, linear, and leather) was pretty well established (known). What you describe from your observations seems to not allign with the existing research. So I am curious whether you have encountered some genetic oddity or if we are having some miscommunication or if there are other factors in play there that would square the two (your observations and the existing research). So a couple of questions, if you don't mind ...

In describing your fry, you mentioned "scaled" and "scaleless". The few that you have shown from the side appear fully scaled except for the shusui that appears to be leather (no scales on the sides). Have you seen any linear fry (koi with a row of scales down the lateral line, but with no scales on the rest of the sides)? If so, how many (or about what percentage)?

Were there any other koi in the pond with your female kohaku and male shusui? And if so, were they fully scaled or Doitsu? And do you think they were male or female? I'm just wondering if there could be a fully scaled male parent that got into the mix.

Linear and leather koi each carry the dominant and recessive Doitsu (German) gene pair (Nn) according to the research. If they had nn, they would not be Doitsu and could not be linear or leather. If they had NN, they would be dead. So the odds of them passing on a dominant Doitsu gene is 50-50. If you breed any fully scaled koi to an Doitsu koi (whether linear or leather), about half of your fry should be Doitsu.

I've read that Doitsu average to be a little smaller and weaker early on than fully scaled. So some may get eaten by the fully scaled ones, resulting in the number of Doitsu being a little less then half. In my experience that has not been very noticeable.

Is it possible that you may have culled lots of Doitsu fry, either because they were smaller and weaker or for whatever reason did not look good to you, leaving you with mostly fully scaled koi?

Thanks. I just find this puzzling, and am curious to understand what has happened and how.

[Matt24]

Here is a short video of my favorite patterned fish thus far:
https://youtu.be/S4cpQ0Xjd5c?si=CfxInLAzEd-AXvKd

That certainly an interesting pattern, and on a sturdy, well built little koi (who does not like the net!).

[Coldspringsfarm]

In another thread you mentioned ...



I don't know much about how Kohaku and Shusui patterns interact. However, I thought the science and research of scalation (fully scaled, scattered, linear, and leather) was pretty well established (known). What you describe from your observations seems to not allign with the existing research. So I am curious whether you have encountered some genetic oddity or if we are having some miscommunication or if there are other factors in play there that would square the two (your observations and the existing research). So a couple of questions, if you don't mind ...

In describing your fry, you mentioned "scaled" and "scaleless". The few that you have shown from the side appear fully scaled except for the shusui that appears to be leather (no scales on the sides). Have you seen any linear fry (koi with a row of scales down the lateral line, but with no scales on the rest of the sides)? If so, how many (or about what percentage)?

Were there any other koi in the pond with your female kohaku and male shusui? And if so, were they fully scaled or Doitsu? And do you think they were male or female? I'm just wondering if there could be a fully scaled male parent that got into the mix.

Linear and leather koi each carry the dominant and recessive Doitsu (German) gene pair (Nn) according to the research. If they had nn, they would not be Doitsu and could not be linear or leather. If they had NN, they would be dead. So the odds of them passing on a dominant Doitsu gene is 50-50. If you breed any fully scaled koi to an Doitsu koi (whether linear or leather), about half of your fry should be Doitsu.

I've read that Doitsu average to be a little smaller and weaker early on than fully scaled. So some may get eaten by the fully scaled ones, resulting in the number of Doitsu being a little less then half. In my experience that has not been very noticeable.

Is it possible that you may have culled lots of Doitsu fry, either because they were smaller and weaker or for whatever reason did not look good to you, leaving you with mostly fully scaled koi?

Thanks. I just find this puzzling, and am curious to understand what has happened and how.

I'm going to try to answer your questions from memory as Tapatalk doesn't make it easy to flip back and forth.

Parents - I have included a video of all of the koi that were present for the spawn. The two Kohaku are definitely both females and are fully scaled. Of the 3 Shusui, the darkest one is definitely male and I witnessed him participating in the spawn. He is, unfortunately, the ugliest parent I own with large and very dark "dragon" dorsal scales. I guess the rest of his scales would be considered "scattered" but there are some along the lateral line. The lightest Shusui is still sex to be determined and is leather. I never saw it participate in either spawn other than gorging itself on eggs. The third Shusui is definitely female. So I can confidently say that a fully scaled male was not involved.

Culling - With this group, there was no culling until last week. There were, of course, a small percentage that were slow to develop and a few deaths along the way. I have actually been impressed with the growth rates and uniformity of this group of fry from the beginning. As for last week's cull, I was very careful to review every fish for scale patterns and 99-100% were fully scaled. The two doitsu fish I did find may very well be cross contamination from the Shusui spawn fry. There were about 300 culls which got rejected due to lack of pattern(solid white or orange), small size, and deformities(mostly missing gill plates).

https://youtube.com/shorts/B-PUhk6Gn...HHqoFdEG<br />

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[Matt24]

Thanks very much for the information on this puzzle. You might have already been thinking this, but a couple of things you mentioned lead to a theory ...

Of the 3 Shusui, the darkest one is definitely male and I witnessed him participating in the spawn. He is, unfortunately, the ugliest parent I own with large and very dark "dragon" dorsal scales. I guess the rest of his scales would be considered "scattered" but there are some along the lateral line. ... a fully scaled male was not involved.

... I was very careful to review every fish for scale patterns and 99-100% were fully scaled. The two doitsu fish I did find may very well be cross contamination from the Shusui spawn fry.

So IF the two Doitsu fry or their eggs just rode over on a net or something, then there might have been zero Doitsu fry in that Kosui spawn. While I have not seen a close photo of the sides of the male parent, your description of his scales combined with the scalation of the results of the spawn makes me wonder if he is not really a Doitsu at all. Perhaps genetically, he is a scattered scaled koi, and therefore has no "N" gene to produce Doitsu fry. Maybe he just has enough scales around the lateral lines to kind of resemble linear scalation.

IF so, he would be ssnn. The fully scalled female would have to be SSnn or Ssnn. If she were Ssnn, and he is ssnn about half the fry would be fully scaled, and the other half would have scattered scales. So I bet she is SSnn. The double dominant S gene would mean every fry gets one, and there should be none with scattered scales. Also I suspect Japanese breeders trying for fully scaled koi would tend not to use oyagoi that give them some scattered scales. If so, that would mean imported fully scaled koi would be much more likely to be SSnn than Ssnn.

Now as for why hardly any of the fry look dark like dad, I have no idea, though I think there was one kind of greyish in your tub that you showed.