Yesterday we took a look at Dutch aquariums, so I thought that we could make this week all about theme aquariums! For the next four days, we’re going to dive in the various aquarium styles that currently dominate the hobby.

Today’s article will highlight Iwagumi aquariums, which is Japanese for “rock garden.” Considering how popular zen rock gardens are in Japanese art, it shouldn’t be surprising that they applied the same aesthetic to aquariums. But don’t be misled by the comparative simplicity – Iwagumi aquariums are actually governed by a number of rules and guidelines. There are different types of rocks, and each has its own unique name and purpose.


Iwagumi Stone Types

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The Oyaishi stone is the focal point. It is always the largest and most beautiful stone, so it serves to draw the eye inward to a dominant aquascape feature. Essentially, every other rock and plant in the aquarium serves to highlight or draw more attention to the captivating Oyaishi.


Iwagumi Style Planted Aquarium

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If the Oyaishi is Batman, then the Fukuishi is Robin. The Fukuishi stone is smaller than the Oyaishi, but is still larger than the other stones in the aquarium. It should have the same color and general shapes as the Oyaishi in order to highlight the larger stone’s beauty.


Verdant Iwagumi Aquarium

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These are the tertiary stones, which help to even out the aquascape by giving it a more rounded-out appearance. Two stones would be too stark and artificial, so balancing out the scene with smaller rocks give it a much more natural, organic feel. This technique takes a page out of Takashi Amano’s book with an emphasis on natural chaos.


Also called the “sacrificial stone,” the Suteishi is a small stone that can be obscured or even entirely consumed by plantlife. The sacrificial stone helps to create complexity and subtlety by hiding some of the aquascape’s features.

Iwagumi Aquarium with a Focus on Rocks

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Those are the basics of an Iwagumi aquarium, but past that it’s up to you to find the perfect arrangement. Some Iwagumi style aquariums place a heavy focus on the rocks. Other Iwagumi aquariums, like the one show below, take a slightly more organic approach by creating a partnership between the plants and the rocks. The rocks in this aquarium are certainly a prominent feature, but the aquatic grass is just as eye-catching as the Oyaishi.

Iwagumi Style Aquarium with Heavy Plant Life

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Iwagumi aquariums would be perfectly suited in areas that require people to de-stress. Install an Iwagumi aquarium in your office to create a zen-like aquascape that will diffuse office tension, or place one of these aquariums in the lobby of your business to help place customers’ minds at ease. At home, Iwagumi aquariums would be ideally suited for bedrooms or reading rooms. Sit back, kick up your feet, and let the stress of a busy day melt away with a soothing aquatic zen garden.