How Big Do Ogon Koi Get?

Orange Ogon Koi (Cyprinus carpio) with specks of black and white fins swimming at the surface of the water in an ornamental pond

There are many types of koi fish available. Some are sought after because of their friendly natures, such as the Chagoi, while others, such as Ogon koi, are desired for their beauty. Ogon koi provide a striking appearance in your fishpond. They come in various colors, but orange and platinum ogon koi are the most popular. Now, you might wonder how big an ogon koi can get.

Ogon koi will typically grow to be about 15 to 18 inches long, depending on how big the pond is and how well it is taken care of. While other koi varieties grow much bigger, ogon koi are desired for their beautiful appearance. Some older ogon koi can grow much bigger.

This article discusses the factors influencing how big an ogon koi will grow. We will also discuss some tips for choosing a good ogon koi based on its appearance and characteristics. Ogon koi are highly sought-after fish, but some might be more valuable than others. So read along to find out how to ensure your ogon koi grows as big as possible.

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How Big Do Ogon Koi Grow?

Orange Ogon Koi (Cyprinus carpio) with specks of black and white fins swimming at the surface of the water in an ornamental pond
Orange Ogon Koi (Cyprinus carpio)

There are almost 100 different species of koi fish, but they were all cultivated from wild koi fish found in Japan. With time, these wild koi were bred for specific characteristics. Ogon koi is no exception, as these fish were bred for their metallic color.

Ogon means golden, and the ogon koi gets its name from its golden metallic-colored scales. Many varieties of koi fish are classified as ogon koi. However, the most popular ogon koi are Purachina ogon, known as platinum ogon, and Yamabuki ogon, or bright orange ogon. Cream-colored ogon are extremely valuable because they are so rare. Therefore, the platinum and orange ogon varieties are the most popular.

Koi - YAMABUKI OGON swimming in front of a white background
Yamabuki ogon Koi fish

Ogon koi are recognizable by their solid colors and metallic scales. They don’t have any spots or blemishes on them. Some ogon koi have been cross-bred with fish that have gin rin scales. As a result, they not only have a metallic finish but also have a diamond-like shine due to the protein folds under their scales.

Regardless of their breeding, most ogon koi grow to be about 15-18 inches long. However, other factors determine how big your ogon koi will be and how fast it will grow to be that size. Note that an ogon koi will never grow bigger than it is genetically capable of.

However, koi fish raised in captivity tend to be smaller than those raised in the wild. Ogon koi raised in Japan tend to be bigger than koi grown in the west. Japanese ogon koi can grow as big as 26 inches. For this article, however, we are discussing ogon koi grown in aquariums and fishponds, which will be about 18 inches long. So, what factors influence the growth of an ogon koi?

Gold and White Ogon Koi Swimming at Edge of Pond
Gold and White Ogon Koi Swimming at the Edge of the Pond

1. Water Temperature Influences The Growth Of Ogon Koi

Ogon koi will grow faster in an aquarium than in a fish pond. This is because the water temperature in aquariums is slightly higher and has fewer fluctuations than in a fishpond.

In Japan, ogon koi are kept in outdoor ponds and hibernate under a layer of ice in the winter. They’re able to survive this because their metabolisms adjust. However, the result is that Japanese-bred ogon koi grow much slower than western-bred ogon koi. On the flip side, the slower growth rate of Japanese-bred ogon results in a longer lifespan.

On average, ogon koi can live for up to thirty years. However, the faster they grow, the shorter their lifespan. Regardless, ogon koi prefer a water temperature of 75-80°F. Therefore, if you want your ogon koi to grow fast, ensure the aquarium or pond temperature remains within these limits.

2. Stress Influences The Growth Of Ogon Koi

Although ogon koi are hardy and can adjust to various water conditions, their growth stagnates if they’re subjected to stressful conditions for long periods. These are some of the factors that make ogon koi stressed:

  • Fluctuating water quality
  • Unsuitable water temperatures
  • Diseases
  • Overcrowding
  • Underfeeding
  • Poor oxygenation in the water
  • Incompatible fish species

When ogon koi are subjected to stressful conditions, their growth might be stagnated. In addition, stressed ogon koi are more susceptible to diseases and parasites. Therefore, to keep your ogon koi healthy and thriving, minimize the stressors they’re exposed to.

3. Food Quality Influences The Growth Of Ogon Koi

Ogon koi require a diet high in macronutrients (protein, fats, and carbs) to grow and be healthy. In addition, ogon koi need plenty of vitamins and minerals in their diets. Therefore, feeding them high-quality koi food is the best way to ensure a healthy growth rate and healthy fish.

Switch between the types of food you feed your ogon koi, as their growth might stagnate if they’re constantly fed the same food. In addition, be sure to feed them enough food – ogon koi are greedy eaters. If you underfeed your ogon koi, they’ll quickly become stressed. On the contrary, overfeeding also leads to health problems.

Therefore, ensuring your ogon koi are fed enough food and food of high quality is one of the best ways to ensure they grow big and are healthy.

4. Tank Size Influences The Growth Of Ogon Koi

Golden yellow Ogon Koi carp Cyprinus rubrofuscus `koi` fancy fish swimming in aquarium. Ogon is a metallic koi of one color only hikarimono. The Japanese name means `gold
Golden yellow Ogon Koi (Cyprinus rubrofuscus) swimming in an aquarium

It’s often been said that tank size determines how big your fish will get. That is not true, as genetics is the primary determiner of fish growth. However, the size of your tank or pond will determine how fast your ogon koi grows. An ogon koi requires a pond that holds between 400 and 500 gallons of water to grow quickly.

In addition to the size of the pond, other species of fish in the pond will also affect how your ogon koi grows. Comet goldfish, catfish, killifish, and minnows are good companions for ogon koi. However, bluegills, rasboras, and danios will compete for the ogon koi’s food, making them stressed and causing a slower growth rate.

Therefore, having a big enough pond to support your ogon and choosing the right accompanying fish to place in the tank will influence how fast your ogon koi grow. These are the four main factors that influence the growth rate of an ogon koi. However, the maximum size of an ogon koi cannot be altered, as it is genetically determined.

Now, you might be wondering what to look for when buying an ogon koi and how to choose an ogon koi of exceptional worth.


How To Choose A Good Ogon Koi

Gold and White Ogon Koi Swimming at Edge of Pond
Ogon Koi Swimming in a pond

As we have mentioned, the maximum size of an ogon koi determines by its genetics. Japanese-bred ogon koi tend to grow slightly bigger than Western-bred ogon koi. However, the size of the fish is not what makes ogon koi special.

When looking for a high-quality ogon koi, you must look at the uniformity of its color. A high-quality ogon koi will have a single, uniform color stretching from its head to its tail. Neatly aligned scales are another thing to look for. Any blemishes, markings, or misaligned scales will decrease the value of an ogon koi.


Ogon koi grow to be about 15-18 inches long. However, Japanese bred ogon can grow to be about 26 inches long. While the size of the ogon koi is not why it is so sought after, various factors influence how fast an ogon koi will grow.

Water temperature, stressors, food quality, tank size, and accompanying fish determine how fast your ogon koi will grow. When purchasing an ogon koi, look for one with a uniform color and neatly aligned scales.


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