What is Iwagumi?

What is Iwagumi?

Iwagumi is a common term used in aquascaping. It refers to a traditional style of underwater landscaping wherein the only hardscape material used is stone. This gardening technique was introduced by the Japanese. The stones are positioned in the garden in such a way that it provides the structure of the seascape. These stones are combined with shrubbery and sand to create images of a mountainside or the shores of a lake. This landscaping style became a huge influence in aquascaping. The simple and amazing formations became the inspiration of a lot of aquascapers.

iwagumi aquascape

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There is no limit on the number of stones you will want to use in the execution of the Aquascape design but the least number of stones is 3. The arrangement using just 3 stones is called Sanzon Iwagumis. It is said that placing just a few stones into the design imbibe a remarkable and symbolic style while adding more stones makes it look more intricate and complex.

It is better to use an odd number of stones to create a more natural and appealing look. This will prevent the design from being split in the middle. When an even number of stones are used in the design, the tendency is to put an equal number on each side of the scenery. This makes the design look unappealing. By using an odd number of stones, the tendency to make the design look symmetrical is avoided. There is beauty in chaos. Uneven numbers create a pattern of unpredictability.

The Functions of the Rocks Used in Iwagumi


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In Sanzon Iwagumi, there are 3 stones being used. The largest stone is placed in the middle flanked by two smaller stones. It resembles the Buddhist triads. This seascape design is given a very elegant and majestic atmosphere to its viewers.

Each rock has a name and a specific function. These are the Oyaishi, Fukuishi, Soeishi and Suteishi.

The Oyaishi represent the natural flow of water. The main stone is usually the prettiest and the biggest. It should have a height of around two-thirds of the aquarium so it stands out when you plant it upright. Using the Rule of Two-Thirds, the primary stone should have this height to appeal to the naked eye. The stone should also be placed slightly tilted so that it creates a fluid look as if it was going to the water. The positioning of the rock should look as natural as possible.

The second largest stone is called the Fukuishi. It is positioned on either side of the main stone or Oyaishi. This stone must have the texture and type similar to that of the Oyaishi.

Soeishi, the tertiary stone must be planted beside the Oyaishi, on the opposite side of the Fukuishi. The role of this stone is to complement the appearance of the main stone by highlighting it. By acting as its accessory, the powerful vibe of the Oyaishi is emphasized.

Finally, the Suteishi or the sacrificial stone. It looks like a random stone strewn down on the sand bottom that will be eventually be covered in time. This stone can be omitted from the design but it does add a subtle effect of being complex and intricate at the same time.