Every grow-out starts with a decision. Not just which fish to keep, but why they are worth the time, space, and patience required to see them through properly. This particular Kohaku grow-out begins at Saito Fish Farm, and while Saito may be considered a small breeder by Japanese standards, what he consistently produces tells a very different story.
This batch of Tosai arrived at the back end of 2025 and immediately stood out—not because of loud patterns or finished colour, but because of the underlying qualities that matter most when selecting Kohaku for the long term.
Before getting into the finer details, the full selection process and background behind this batch can be seen in the video below, which follows the fish from quarantine through to final selection for the grow-out pond.
A Small Farm with a Clear Focus
At Saito Fish Farm, Kohaku is not just another variety—it is the foundation of the farm. Years of careful parent selection and refinement have gone into developing a line that prioritises structure, skin quality, and long-term development rather than short-term visual impact.
What makes this particularly interesting is that Saito works without the scale or infrastructure of larger breeders. There is limited indoor growing space, and most development relies on careful planning rather than volume. As a result, every parent fish matters, and every pairing has intent behind it.
That intent shows clearly when assessing these Tosai.
Bloodlines That Have Been Watched and Refined
This batch represents the third year of using a newer female line, originating from Dainichi Kinsen, itself coming from Dainichi Toyota. That female has been paired with Saito’s established Kohaku line, built on a long-standing mix of Dainichi, Junior, and Momotaro genetics.
This is not a first attempt or an experiment. These fish are the result of years of observation, adjustment, and refinement. Having watched the parent fish develop over time, there is a strong level of confidence in what these Tosai can become—even if they do not look particularly dramatic at first glance.
Early Development: Looking Past Colour
At around six months old and averaging between 20–23cm, these Tosai are still very much in their early stages. They have had no colour-enhancing food and have been kept in low-light conditions, meaning the beni is soft, pale, and often orange rather than red.
That is exactly where Kohaku Selection begins.
Rather than focusing on pattern or finished colour, attention is placed on:
- Skin quality and shiroji purity
- Beni thickness and consistency
- Sashi and kiwa development
- Head shape, mouth size, and overall frame
- Bone structure that supports future growth
These are the traits that define strong Gosanke koi carp, and they are far easier to assess early on than many people realise.
A Stricter Approach to Selection
One of the biggest changes in this grow-out is a deliberate reduction in numbers. Instead of starting with 150–200 fish, fewer than 100 Tosai were selected to move forward.
This wasn’t about removing “bad” fish—far from it. Plenty of good Kohaku were left behind. But when the goal is long-term development, lower stocking density allows for:
- Easier water management
- More consistent growth
- Better use of space and filtration
- Clearer assessment at future selection points
The focus is firmly on quality over quantity, and that mindset shapes the entire project.
Why Saito Kohaku Punch Above Their Weight
What becomes clear during selection is just how often these fish show traits more commonly associated with much larger operations. Head size, frame balance, and skin quality consistently exceed expectations for Tosai from a small farm.
This is where Saito Fish Farm really stands out. The fish may not always shout for attention at first glance, but the foundations are there—and that is what matters most when raising Kohaku properly.
The real test now comes from environment. With indoor growing facilities and controlled conditions, this grow-out aims to explore just how far these genetics can be pushed when given the opportunity Saito himself doesn’t have the space to provide.
Looking Ahead
This is only the beginning of a 12-month journey. Future updates will track growth, structure changes, and how the beni develops over time. The results will speak far louder than predictions ever could.
For anyone interested in understanding Kohaku Selection at a deeper level, this project offers a rare look at what truly matters beneath the surface.
Exploring Japanese Koi Further
If you are looking to explore high-quality Japanese koi beyond this grow-out project, you can view current availability here: