Koi Carp Size & Growth Chart

If you are looking to adopt some amazing koi carps, you certainly know already that these fish are not just beautiful. In fact, they are also long-living creatures that can grow to fairly large sizes.

by Fabian

Updated: September 1, 2021 / 5 mins read

Fabian is the dedicated Chief Editor at Aquarium Nexus. From a young age, he was captivated by the vibrant world of aquatic life, leading him to accumulate over 20 years of experience in keeping and breeding various fish species. The fulfillment derived from the aquarium hobby has remained a constant throughout Fabian's life. As an expert in the field, he finds great pleasure in imparting his extensive knowledge and personal experiences to both seasoned aficionados and budding enthusiasts.

Moreover, they are one of the largest fish pets which one can even own these days, and that is exactly why most people keep them in outdoor ponds. And sometimes, even ponds can become too small for these mesmerizing beings, so planning ahead is important.

In order to know your pets and their growth rate over time, we have prepared a dedicated article on the topic.

How Fast do Koi Grow?

Koi fish can be considered as fast growers if we take in consideration their fairly long lifespan. Indeed, most of the sub-species usually manage to reach their full size by their third year of life, with only slightly further growth during the rest of their life expectancy.

Additionally, it is important to know that some types grow to a much larger size than others, but also that females tend to have wider bodies when compared to their male companions. Indeed, females start carrying eggs once they reach maturity, so they obviously have a wider body because of that.  

That said, if we want to put some general observations and predictions in a chart, it will look as the following one.

The indicated expected predictions are subject to many factors which can change them drastically sometimes. For instance, there are some koi carp types which are genetically predisposed to reach a larger size when compared to other types.

Also, environmental factors such as food quality as well as the size of the pond may also greatly contribute into defining the growth rate of each individual koi carp.

How Big do Koi Grow?

Koi fish grow large. Depending on the type and other environmental factors, you can expect your colorful pets to reach a full size of around 20 inches. However, some Japanese varieties can surpass that and reach a size of even 36 inches in body length. And not to mention that some special kinds can obtain a fascinating body length of 52 inches.

But koi fish do not just grow large. Indeed, they also grow pretty fast, especially if we take in consideration their long lifespan. By their third year of life, they are mostly fully grown ornamental beauties. That means that they have a monthly growth of almost an inch (or 2 centimeters).

How to Make Your Koi Grow Bigger?

Koi fish depend a lot on their environmental and nutritive factors, so there certainly are a few handy tricks which you can apply if you want to enhance their size.

1. Give them the Space

Let us begin with the very basics. If a fish does not have the space to grow, it will not grow. It is as simple as that. Therefore, please plan ahead before even adopting these mesmerizing creatures.

Having a tiny pond may seem ideal to house smaller koi fish in it, but it is important to know that this is not a long-term solution. Once fish reach their full size, they will require proportionally larger swimming areas. And if these are not provided, the koi carps will be limited in their growth.

Additionally, small ponds are not the only factor which can limit their development. Indeed, this is also valid for overcrowded ponds. Even if you have a decently sized pond, you need to make sure that each of your koi carp has at least 250 gallons of water at its disposal.

To conclude, the basic predisposition for making your koi grow bigger is giving them the space for it.

2. Feed them with High-Quality Food

As with any other living being, what we eat is what we are. Feeding fish with low nutritional meals can only bring them to having a worse health state. And, consequentially, less predispositions to grow. Therefore, only choose high-quality food for your precious fish, even if that means paying a bit more for it.

Also, remember to never overfeed your koi carps. These fish do not own a stomach, so it is vitally important to feed them with small meals only, but more often. This can ensure a healthy development and a larger body size in the near future.   

3. Keep your Water Clean

Clean water is the ultimate condition not just for a larger growth, but also for a healthier lifestyle. Therefore, plant to invest into a powerful filtration system.

How to Make Your Koi Grow Faster?

If you are looking to make your koi fish grow faster, you should start during their earliest life phase. Thinking that they can temporarily live into a small pond for a couple of years and then magically starting to grow amazingly fast is completely wrong.

Space, protein-enriched food and warmer water temperatures (from 75- do 80-degrees Fahrenheit) will become your best allies in accelerating the growth of your koi fish.

Can You Keep Small Koi in Aquarium?

Absolutely, as long as they have enough space to move freely. Smaller types of koi carps, as well as juvenile specimens, can be kept indoors. However, please do not expect these fish to grow much once you move them to an outdoor pond. As already mentioned, the best starting period to promote the growth of koi carps is during their youngest life phase, not after that.

Wrapping Up

Koi fish are quite spectacular pets, and it should come as no surprise knowing that they make one of the top choices when it comes to outdoor ponds.  

If you are looking to grow some decently sized specimens, it is actually not that complicated. All you have to do is to basically take really good care of them. And to have some luck, as genetics also play an important role in this story.