Koi Varieties – Aka Matsuba

Our newest blog post is the first in a trio of posts all about Matsuba koi. Matsuba koi are a sub-variety of koi that are all single-coloured koi with a black net-like reticulation pattern, some Matsuba varieties, such as Gin Matsuba and Kin Matsuba, are metallic koi while other Matsuba varieties, such as Ki Matsuba and Shiro Matsuba are non-metallic koi. In this first blog post, we will be looking at the red, non-metallic version of this sub-variety, the Aka Matsuba.


Aka Matsuba koi from breeder Aokiya

The word Matsubagoi (MAHT-soo-BAH-goy) translates as ‘pine needles koi’ and refers to the pinecone-effect seen on a koi when it has reticulated scales. Reticulation means that the scales themselves have a tint to them, resulting in a strong contrast between the skin colour of the koi and the tint colour on the scales. This pattern gives the koi a net-like or a pine-cone appearance.


Matsubagoi technically refers to any reticulated koi but is usually only used when talking about a single-coloured reticulated koi. For such fish, we usually add a prefix, such as Aka, to describe the colour of the koi and shorten ‘Matsubagoi’ to ‘Matsuba’.


All Matsuba koi were created in some way from the Asagi variety, which is a blue koi with strong reticulated scales and a hi (red) pattern along the sides of the body. The Aka Matsuba was created from a pairing of a high-red Kohaku (white fish with red markings, the high-red means it is a mostly red Kohaku) and a Hi Asagi (variation of Asagi koi with more red colouration than normal) in the late 1950s. This pairing resulted in a wide range of fry, mostly with reticulation but some without, and a wide range of colours, with blues, whites, and reds visible across the generation. The few fry that had only red colouration were the koi that, with a little refinement, would soon become the Aka Matsuba variety with strong red colouration from the Hi Asagi koi and the Kohaku koi and a good quality reticulation from the Asagi koi.



Pongoi (Best Quality) Aka Matsuba Koi

Aka Matsuba koi from breeder Hirasawa

Firstly, the most important thing to judge in an Aka Matsuba koi is the base colour. Since this koi variety is a single-coloured variety, the base colour should be perfect. The red should be a deep, dark red with a consistent shade all over. Any missing scales, damage or scars will be very obvious on an Aka Matsuba so should be avoided. The deeper and more consistent the colour, the better the quality of the Aka Matsuba and, if the colour is deep and consistent, the most valuable koi of this variety have the darkest red colour. The fins, tail and head should all display the beautiful red colour as well with the colouration ideally extending to the very tips of the fins and the tail. The lower quality Aka Matsuba will often have visible stripes or areas of no colour on the fins or the tail and while these are technically not ideal for this variety, can add interest and patterns and therefore be appealing to many koi keepers.



The other thing to consider when judging an Aka Matsuba koi is the reticulation pattern, specifically the colour and consistency. When a koi has reticulated scales, it means that each scale has a light tint at the base that becomes a darker tint at the top of the scale, resulting in a gradient effect. The colour of this tint varies between varieties, but, typically, the best reticulation occurs when the tint colour is a sharp contrast to the scale and skin colour. For example, in an Aka Matsuba koi, the scales and skin are a deep red and the ideal reticulation colour is a dark grey or black resulting in a strong contrast between the red and the black. This makes the net pattern, or pinecone effect, really stand out on the body of an Aka Matsuba.

Aka Matsuba koi from breeder Otsuka

As mentioned, the colour of the reticulation should be either dark grey or black. Ideally, each scale will have a gradient from grey to a deep, dark black but the darker the top of each scale, the better. Most importantly, however, is that the colours should be consistent. Every scale should have the same light and dark tints and every scale should have the exact same gradient effect. Any single scale out of place, either with different shades in the reticulation pattern, or in the actual position of the scale, will be very noticeable and is considered a big imperfection in this variety of koi. In fact, when considering any reticulated koi, the most important thing is consistency, each scale should have the same shades and each scales should have the same pattern.





The Aka Matsuba is a beautiful stand-out fish where most of the appeal comes from the simplicity of its pattern. A perfect Aka Matsuba can be many times more stunning than many other, more complicated koi and the variety truly highlights how extensive the range of koi fish is and that there is always a koi for everyone, no matter what you like!


To see our current stock of Aka Matsuba koi, click here:


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