Iwagumi Aquascape: Stone Layouts, Rules & Setup Guide

Update: June 2026

Iwagumi (Iwa = stone, Gumi = arrangement) is a Japanese stone‑only aquascaping style. You arrange 3–7 stones in asymmetric triangles. The main stone (Oyaishi) sits at the golden ratio point. Forget the rest until you get this right.

The 5 Main Stones & Popular Types (Cheat Sheet)

Practical tip: Place stones directly on the tank bottom glass, then add substrate around them. Never put heavy stones on soft substrate – they will shift and can crack the glass.

New to aquascaping? Read the Aquascaping For Beginners: 7 Styles & Setup Guide first.

History of Iwagumi

Takashi Amano created the Iwagumi style in 1985, using river stones refined by waves and *Echinodorus tenellus* as the carpet plant. His first composition was a stratospheric success and spawned a global movement.

Since then, Iwagumi has evolved from a niche Japanese technique into one of the most recognized aquascaping styles worldwide. Amano’s core philosophy: stones are the “bones” of the landscape. If you place them right, the rest of the garden appears without help.

Takashi Amano – first Iwagumi Aquascaping 1991

Iwagumi Styles and Basic Principles

The main rule: stones first, plants last. There are 6 core styles within Iwagumi:

1. Fossilized Wood – Uses fossilized wood stones instead of regular rocks, paired with Glossostigma as the carpet plant. This was the original style Amano showcased in 1991. It never became mainstream because the material is expensive and hard to find.

2. Sanzon – The classic 3-stone Buddhist triangle. The main stone (Oyaishi) sits at the Golden Ratio point. The secondary stone (Fukuishi) is placed to the right and slightly behind. The auxiliary stone (Soeishi) is placed to the left and slightly behind. The aspect ratio of the resulting triangle should be 2:3 from left to right. This is the most popular Iwagumi style for beginners.

3. Sand Sanzon – Same as Sanzon, but with decorative sand (often ADA Borneo or silica sand) raked in the foreground. The sand creates the illusion of a riverbank or seashore, adding depth and contrast to the stone arrangement.

4. Rays – Sharp, thin stones arranged to radiate outward like sun rays. The tops of the stones always point upward. This style is visually striking but unstable and difficult to execute. It’s rarely used in practice because the stones tend to look unnatural if the balance is off.

5. Mountains – Stones arranged to imitate natural mountain ranges, peaks, or reefs. Unlike other Iwagumi styles, the stones here are placed more horizontally, creating a panoramic effect. This style works best in long tanks (90cm+).

6. Twins – Two massive, often equivalent stones serve as the dual focal point. This is the most expressive and “shocking” Iwagumi variation. It breaks the traditional odd-number rule but still follows the principles of balance and asymmetry.

Classification and Names of Stones in Iwagumi

See the cheat sheet above for Oyaishi, Fukuishi, Soeishi, Suteishi, and Sanzon.

Interesting fact: Those of you, who always think about the importance of the names, will be happy to know that by placing stones in a certain position, one should symbolize the admiration of the Buddha. 

Main Rules for Stones Placing by Takashi Amano

2. Never put an even number of stones. You can only put an odd number of stones, i.e. 3, 5 or 7. Never put an even number of stones. You can only put an odd number of stones, i.e. 3, 5 or 7. Takashi Amano always said that the odd number of stones makes the process of creating a natural landscape easier since it is difficult to create symmetry from an odd number of elements.
3. Never put stones of the same size and shape.
4. Do not use stones of different colors or from different areas in the same aquarium.
5. Never place rocks and driftwood in unstable and unnatural positions. The natural look should be the foundation of any composition in aquascaping.
6. Never put stones in a row; by doing so you will simply destroy all the volume of the entire composition.

Key Rules for Groups of Stones by Takashi Amano

1. Stones are always placed in groups. There may be several groups in the aquarium.
2. Only one of the five main types of stones can be used in each group of stones (except the third item). The remaining stones of each group should have a different shape from the main one and simply complement it.
3. One can use 2-3 stones of the five main types within a group, but they have to be slightly different in size. Those are Male and Female stones.
4. Groups of stones shall consist of two or three pieces of the same basic type, which can be combined into a large composition to create a larger focal point.
5. Never use stones in the following cases:

• If they are damaged or have been cut off;
• If the top of the stone is larger than the base (except for arched and branching stones);
• Never put vertical stones horizontally and vice versa;
• If the stones have different structure and type (this will affect the continuity and harmony of the entire composition);
• If the stones have a different structure; e.g., never mix stones refined by the water (coastal) with the stones with sharp edges (from mountains);
• Never put the stones in such a way to locate the symmetry axis of the stone at a right angle to the walls of the aquarium.

5 Types of Main Stones in Iwagumi

These 5 shapes describe the stone’s silhouette, not its role in the composition.

1. Low vertical (Soul and Reishoseki stones). The base is much wider than the tapering tip. This is one of the most popular stones.
2. Tall vertical (Body, Taidoseki). This is the vertical stone with the base, which is a bit wider than the top. This is the highest stone in the group. In addition, it defines the mainline of the garden motion within the composition. It’s recommended to avoid putting it ahead of other stones!
3. Flat stone (Heart stone, Shintaiseki). In complex compositions, it’s used as a central harmonizing element, while in simpler compositions; it serves to harmonize vertical stones with horizontal lines of land or water.
4. Branching stone (Shigyoseki). This is a stone that breaks all the rules. The top is flat and slightly wider than the base. In the most difficult case, the top is too large and looks unstable.
5. Reclining stone (Ox stone, Kikyakuseki). The height of this stone is between the flat and branching stones. In other words, it can’t be lower than the flat one, and higher than the branching one. One edge of the stone is higher than the other. This is a fine stone placed in the front to combine other stones. In addition, it has to be placed very carefully. 

Types of Stones for Iwagumi

For the 5 stone shapes (low vertical, tall vertical, flat, branching, reclining) – use them as described above in the cheat sheet.

In his works, Takashi Amano often used the following types of stones:

Manten stone

This is one of the most popular stones belonging to the premium category. There is an opinion that these are the most ideal stones for building classic Iwagumi compositions. This stone is characterized by sharp edges, angular shapes, unique textures, and a velvety surface. All these features give this material an astonishing look of natural rocks. Most of the fragments of this stone have warm colors, but each individual stone may differ from others in hue.

Yama stone

These stones can significantly enhance the feeling of the vast space and scale of the composition in the aquarium. Even small stones evoke an awe-inspiring sense of great age, resembling mountain boulders carved by winds and rivers.

This stone is characterized by a smoothed pattern. Its texture is quite uniform, so it’s better to arrange them randomly (scatter), rather than select the most attractive parts of the sides of individual stones.

Seiryu stone

This decorative stone is considered one of the most beautiful for aquariums. Gray and silver colors combined with sharp angles allow you making a lot of things and even creating a miniature mountain range.

Important note: Seiryu Stone contains small cavities with calcium, which may slightly increase the pH level in the aquarium. However, it’s not the biggest deal because it can be easily controlled.

Ryuoh stone

This is a truly beautiful stone with a fancy shape and an intricate surface. It’s ideal for use in Iwagumi style aquascaping.

This stone imitates the top of rocks or low-lying mountain surfaces. It’s often used in complex compositions with driftwood. It creates depth and naturalness of the scenery. To create such a layout, it’s important to pay attention to the ridgeline and the continuity of the stones.

Ohko stone (Dragon stones)

The stone itself is fossilized clay. It was originally mined in Japan in the coastal part of natural reservoirs. In a while, deposits were discovered in the United States, Canada, and the United Kingdom.

The main advantage of this stone is its appearance. All holes on the surface are oriented in one direction, as created by nature itself with the help of water. Visually, the Dragon Stone resembles a rock covered with dragon scales. It usually has a greenish-brown hue and is lighter in weight compared to other stones used for aquascaping.

Its surface, dotted with craters, is ideal not only as a base for planting mosses or other plants but also as a home for small aquarium inhabitants (dwarf crayfish and shrimp).

In addition to the main stones, one can also find the following types in the Iwagumi style: Frodo stones, Nyasa stones (Chinese Zevra rock), Shou stone, Cliff stone, Wood stone, Yamaya stone, and Black river stone (Hakkai). 

Choosing Stones for Iwagumi

In aquascaping, stones with natural cracks, pits, and uneven surfaces are preferred – as long as they are not broken or artificially cut.

It’s very important that all selected stones are of the same type and color for Iwagumi. In fact, this is one of the main rules, because only the stones, which can create the impression that they were scattered into pieces many years ago after spending an eternity as a whole, can look natural. 

Quarantine new stones: Boil them or soak in hot water for 30 minutes. This kills any hitchhikers (algae spores, planaria, pest snails). Never use soap or chemicals – they will leach into your tank.

Key Mistakes of Beginners When Choosing Stones

1. Beginners often try to choose only the most beautiful stones. However, when selecting the most beautiful stones, their beauty will be lost. Nothing will attract the eye of the viewer if they are all the same.
2. Small stones are not able to show the entire image and are “suppressed” by plants.
3. Too large stones in a small aquarium will disturb the harmony of the composition.

Perfect Iwagumi

In the case of the perfect Iwagumi style, the arrangement of stones is very harmonious and balanced.
During more than a thousand years of history of Iwagumi in Japan, certain laws were created in order to define the correct location of stones. In order to check it and to identify the pattern, scientists analyzed the most popular rock gardens in Japan, which were visited by thousands of people.

It turned out that the ideal arrangement of groups of stones forms triangles between them, and none of the sides of such a triangle intersects the group. And if you try to draw lines between groups of stones, they will resemble the crown of a tree. 

In practice, this means: after placing your stones, step back and check if the triangles look natural. If a line passes through another stone, rearrange.

Why All Stones Have to be Inclined in Iwagumi?

Stones in Iwagumi tilt slightly because water current would tilt them in nature. Takashi Amano said: placement is about speed and intuition, not overthinking.

“You will never create good Iwagumi style until you learn how to place stones as fast as possible. When you spend a lot of time thinking about it, the perception is blunted, and you are already doing something unnatural while losing your sense of rhythm. Experience and some intuition are much more important when arranging stones than artistic taste. It’s very important to develop the ability to see and feel things not with the eyes, but with the heart” — Takashi Amano.

Plants, Fish and Shrimp for Iwagumi

Iwagumi style represents a sense of calm and simplicity. Since the stones are the center of the composition, plants are used to give more strength and power to the stones. That’s why not all plant species can be combined with Iwagumi.

Important: Most carpet plants in Iwagumi require CO2 injection. Without it, you will not get a dense lawn – just stringy growth and algae.

Plants

Iwagumi style doesn’t tolerate chaos in plants. In the majority of cases, only one type of plant is used in the composition. The main thing is that the plants create the illusion of a vegetable “carpet“.

For example:

• Monte Carlo (Micranthemum Tweediei),
• Dwarf baby tears (Hemianthus callitrichoides),
• Cryptocoryne parva,
• Monosolenium tenerum,
• Leaf Micro Sword (Lilaeopsis mauritiana),
• Brazilian micro sword (Lilaeopsis brasiliensis),
• Pygmy Chain Sword (Echinodorus tenellus),
• Riccia fluitans (Crystalwort),
• Staurogyne Spec,
• Marsilea hirsute,
• Pogostemon helferi,
• Glossostigma elatinoides,
• Eleocharis parvula,
• Blyxa japonica.

Fish

Talking about the fish, it’s worth noting that the following species are the most popular for Iwagumi aquariums: Cardinal tetras, Rummy nose tetras, or Harlequin rasboras.

It’s important to use calm fish while avoiding gregarious fish. This helps to maintain a more relaxed environment. It’s not recommended to use shy species, as well as those that prefer to hide in the thickets of plants. 

Shrimp

Takashi Amano used shrimp of the Caridina multidentata species in his aquascaping compositions to fight with algae. The results of his experiments were so successful that these shrimp were used everywhere. In 2006, this type of shrimp was named Amano shrimp in order to show honor and respect to the true genius in the world of aquascaping.

The transparent color of the shrimp perfectly matches the Iwagumi concept. While removing algae from the aquarium, they never attract too much attention. That’s why other types of shrimp are usually not used in aquascaping. The thing is that their bright colors stand out from the harmony and disturb the atmosphere of the entire composition.

Read my article “Amano Shrimp – Detailed Guide: Care, Diet and Breeding”.

The Sequence of Actions in Iwagumi. Step-by-Step

1. Pour a thin layer of soil (1-2 cm) into the aquarium.
2. Select and set the main stone at the point of the Golden section.
3. Place secondary stones.
4. Arrange auxiliary and decorative stones.
5. Install driftwood (In the rarest cases! In most cases aquarists do not combine stones and driftwood in Iwagumy aquascaping).
6. Put all the plants.
7. Your composition is ready.
8. Cycle the tank and add fish or shrimp if you want to.

Equipment For Iwagumi Aquascape

It is important to understand that without good lighting, CO2 system, CO2 bubble diffuser, and filter, it will be very hard to achieve amazing effects.

Therefore, the list of necessary items (with some examples) looks like this:

FAQ

What is the Golden Ratio in Iwagumi?

The Golden Ratio (approximately 1:1.618) determines where the main stone (Oyaishi) should be placed. Instead of putting it dead center, you place it at roughly 2/3 of the tank’s length from one side. This creates natural asymmetry that mimics how stones settle in rivers.

Can I use driftwood in Iwagumi?

Technically yes, but purists say no. Traditional Iwagumi is stone-only. If you add driftwood, it becomes a “Nature Aquarium” or “Stone + Wood” style. Amano himself occasionally combined stones and wood, but the wood should be subtle and not compete with the stones.

What fish go with Iwagumi?

Small, calm schooling fish that don’t disturb the carpet. Cardinal tetras, Rummy nose tetras, and Harlequin rasboras are classic choices. Avoid bottom-dwellers like corydoras that will dig up the carpet. Amano used Amano shrimp (Caridina multidentata) for algae control — their transparency fits the minimalist aesthetic.

How many stones do I need?

Always an odd number: 3, 5, or 7. Even numbers create symmetry, which looks unnatural. The simplified version uses 3 stones (Sanzon). Most competitive Iwagumi tanks use 5-7 stones for complexity.

What substrate is best for Iwagumi?

A nutrient-rich aquasoil (like ADA Amazonia or Fluval Stratum) capped with a thin layer of sand or fine gravel. The aquasoil provides nutrients for carpet plants. The sand/gravel top layer gives a clean, natural finish. Avoid large gravel — it looks unnatural with the minimalist stone aesthetic.

Why are the stones tilted in Iwagumi?

In nature, water current pushes stones slightly downstream. Tilting stones at a 10-15° angle mimics this natural force. Vertical stones look like they were dropped by a giant — unnatural and static. The tilt creates a sense of flow and energy.

Related articles:

Aquascaping For Beginners. Introduction
How to Set Up a Dutch Aquarium
CO2 in a Shrimp Tank
Shrimp Safe Plant Fertilizers