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Koi Varieties - What to Look for When Buying a Koi

Here at Keruto Koi, we have a lot of koi carp available for you to buy, but how do you choose which ones to take home? Often, you just choose the one you like the most or the pattern you think is most interesting, but how do you choose between very similar fish? And, if you want the best quality fish, what exactly are you looking for?

When you are judging a koi fish, there are 4 things that you need to consider before deciding which fish you want. These are the same 4 things that are considered in the judging of a koi competition or a show so, if you are familiar with each of these, you know that you will choose the best fish each and every time.

Goshiki Koi from breeder Aokiya

These things you need to look at when judging a koi carp are the body, colour quality, pattern, and breeder. Let us consider each of these in turn:

Body and Health

Firstly, the body is often the most important factor in a good koi fish. In fact, in most koi competitions, up to half of the points available are given purely for the body and its conformation to the ideal shape. Size is not as important because a good body shape in a small koi is a very good indication of a good body shape when the koi is fully grown. The best shape is typically described as a tree trunk, so not too thin but also not so large that the fish looks bloated. Ideally, the koi will look strong and muscular rather than fat and overweight. Obviously, a good koi will have no deformities such as a crooked body or missing fins. Finally, the best fish will also have a large, symmetrical head and a thick tail joint.

As well as the actual shape of the body, you should also consider whether the koi looks healthy and strong. You do not want to end up taking home a sickly or injured fish by accident. Ensure that you can watch the fish swimming in a pond or a bowl, whether that be in person or via a video. You want to make sure that the fins do not look damaged and that the koi appears to be able to swim normally with the other fish. If possible, try and watch your chosen fish when it is caught and bagged. The fish should display agility and attempt to evade capture when the net is put in the pond and once the koi is bagged or put in a bowl, you can get a closer look at the fish. You will want to have a good look and ensure that it has no signs of damage or injury at any point on its body.

Colour Quality

Next, you need to consider the colour quality of the koi fish. The requirements here for the best quality koi will change a lot depending on the koi variety you choose. One thing that is always relevant regardless of the variety is the quality of the skin and specifically how bright and lustrous the skin and scales of the fish look. If the skin is dull and discoloured, it can be a sign of many things including, poor quality, illness, or stress – all things to avoid. When it comes to the colour (or colours) of the koi, the most important point is that each colour should be strong and even throughout the fish with no patchiness and a consistent shade through different sections of the fish (if applicable).


The next consideration should be the pattern itself. This will entirely be based on the variety of koi and so there are no overall rules that are applicable for all koi here. If you are shopping for a specific variety, the best thing is to do some research before you look for a koi so you know what the ideal adults will look like and get an idea for the pattern specifics you should be looking for. The only point of note here is that if the koi is not a single-coloured koi, then the edges, the kiwa, of each part of the pattern should be clearly defined and strong. Other than this, the guidelines for the best koi vary depending on variety so you need to look into the specific varieties you are interested in. (Keep an eye out for our ‘Koi Varieties’ blog series for information about specific varieties:


The final thing to consider when judging the quality of a koi, especially a young koi, is the breeder. A koi carp can change a lot over its lifetime and if you are buying young fish, the only way to ensure that you will end up with a good quality adult fish is to know the breeders and buy from the right ones. The breeders have the most knowledge and experience when it comes to selecting the best koi and they will only import young koi if they know that the fish will be of the best quality. Unfortunately, it is no longer good enough that the koi come from Japan. Many newer breeders are less fussy with the fish that they send to the UK, meaning that it is especially important to do your research on the breeder. All of the fish we stock at Keruto Koi are from reputable breeders so you can be ensured that your koi will remain a good quality fish throughout its lifetime.

Jumbo Tosai Showa Koi from breeder Isa

At the end of the day, the best koi for you is the one you like the most. A lot of koi judging is very subjective – the fish that is your favourite may not even be liked by the next person! There are some good guidelines above, but you don’t always need to follow them strictly – if you really like a koi and the body shape isn’t perfect, don’t let this stop you from taking it home!

Hopefully, you have learned a bit about what makes the best koi show winners and how to choose the best koi for your own ponds. Have a look here at our current stock of koi for sale:

Keep an eye out for our ‘Koi Variety’ blogs where we will be looking at different koi varieties in turn and talking a little about their histories and what a perfect example of each variety should look like.

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