What is the Ideal Koi Depth?

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Myth or fact that koi depth affects koi fish growth? In this article we will discuss about it so read until the end 🙂

When making a koi pond, don’t forget to determine the depth of the pond water according to the length of the koi being kept. Small koi fish, or those measuring under 15 cm, do not need deep pond water, just 50 cm is enough. Unlike large koi fish or those measuring over 50 cm, of course they need a deeper pond. It’s different again with koi fry which must be kept in a shallow pond.

The growth rate of koi fish is closely related to the activity and behavior of koi in swimming.

Fish BehaviorWhat makes Koi fish grow faster? One of them is by looking at their behavior. Koi fish that swim actively will grow faster, when compared to those that move slowly or are still. That is why sufficient space is needed.

Koi fish that tend to move quickly usually use their tail fins when swimming, while fish that move slowly usually use their pectoral fins and anal fins when swimming. The difference in the use of these fins will affect the swimming speed and growth of the fish.

Koi fish swimming speed

1. Sustainable speed

Sustainable swimming speed is the swimming speed of fish where the fish swims continuously without significant pressure.

2. Prolong Speed

Prolonged swimming speed is the swimming speed of fish where the fish swims while maintaining its stability and swimming endurance.

3. Maximum Speed

Maximum swimming speed is the highest swimming speed that can be produced by fish by providing large current pressure where the fish produces small endurance.

4. Burst Speed

Burst swimming speed is the swimming speed of fish that is formed because the fish is shocked or jolted and occurs in a short time.

So the conclusion is that koi fish can grow optimally if they are in a container or pond with sufficient space to move around, so that they can carry out all their activities.

Tail as the Main Driver

As explained above, the swimming speed of Koi fish relies on the movement of its tail. The harder the tail is flicked, the faster the Koi swims. Koi that have a strong tail can certainly swim fast. The strength of the Koi tail is marked by the base of the tail or what is known as ‘Uzutsu’

Therefore, to predict whether a Koi has the talent to become big (Jumbo) is by observing the base of the tail (uzutsu).

Vertical Swimming Movement

Another factor that can support the growth rate of Koi is vertical swimming activity. This vertical swimming movement usually occurs when the Koi fish are at the bottom of the pond, then suddenly you feed them, then the Koi’s swimming movement from the bottom of the pond to the surface to take the food is done vertically quickly.

The Koi’s movement in swimming vertically is what causes reactions in the muscles and bones and will accelerate their growth. The more often Koi swim vertically, the faster their body length will increase. This is the reason why the depth of the pond is very important so that Koi can swim vertically.

Pond Depth According to Koi Size

1. Koi Fry

For newly hatched koi fish (fry) or under 3 months old, it is appropriate to keep them in a mud pond with a water depth of no more than 40 cm. Why is that?

The first is because Koi fry still do not have the physical ability to swim in deep water. As is known, the deeper the water, the greater the water pressure. Therefore, koi fry will not be able to swim in deep water.

The second reason is because koi fry are in their growth period and need natural food, which is abundant at the bottom of the pond. Therefore, the ideal maintenance pond for Koi fry is shallow, so that the fry can take natural food at the bottom of the pond.

2. Koi Tosai

Koi fish aged between 3 months to 1 year are commonly called ‘Koi Tosai’. During this time span, Koi fish experience very rapid growth. In just a few months, their size can increase by 10 – 20 cm. However, the growth rate will slow down, along with the age of the Koi, or in other words, the older the Koi, the slower the growth rate.

Then the question is “what is the ideal pond depth for Koi Tosai?”Ideally, koi require a pond depth compared to the length of the koi’s body with a minimum ratio of 1: 3. For example, for Koi Tosai with a length of 25 cm, the ideal pond depth is 75 cm.

3. Adult Koi

Adult Koi, which are over 1 year old but under 2 years old, are called ‘Nisai‘. While those aged 2-3 years are called ‘Sansai‘. For Koi aged between 3-4 years old, they are called ‘Yonsai‘ and those aged over 5 years old are called ‘Gosai‘. Adult Koi usually have an average length of between 50 – 60 cm.

The depth of the koi pond for adult Koi should be at least 2.5 – 3 times its body length. For example, if the length of the Koi is 50 cm, the ideal pond depth is 1.25 – 1.5 meters.

4. Jumbo Koi

Jumbo Koi is the term for Koi that is very large and long. Usually measuring above 70 cm. If you want to keep Jumbo Koi, then ideally a pond with a depth of at least 2 or 3 meters is needed.

As additional information, in Japan, Jumbo-sized koi are kept in a fairly large mud pond resembling a lake with a water depth of up to 4 – 5 meters.

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