Name: Mastering Iwagumi: The Art of Rock Formations in Aquascaping
Uploaded: 2026-02-24T16:41:47.000Z
Duration: 14 min 23 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Past simple

You heard me use the word iwagumiwagumi about a thousand times on this channel before.

If you simply want to translate Iwagumi to English, it means rock formation or rock arrangement.

Nowadays, people call Iwagumi any aquarium that has rocks only and no other type of hardscape.

But an Iwagumi was actually developed by none other than Takashi Amano, father of aquascaping.

the style itself has actually changed a lot and has actual route of development.

And we're going to talk through that today.

Well, I'm going to talk you through that today and also I'm going to try to give you some tips on how you can make great Iwagumi scapes.

Doesn't really matter if we are talking true classic Iwagumi or some of the new stuff.

Iwagumi started over 30 years ago now, and

when we visited Japan and visited the ADA Gallery, I was lucky enough to go to the spot on the seaside in Japan where Takashi Amano used to go out and take regular photos about how the scenery changes and how nature forms the rocks on the seaside.

The reason for going back to the same place and taking photos of the same rocks over years as to see how they change, because a lot of stuff in Japanese culture goes back to wabi sabi, which is really difficult to explain.

I don't want to say that I completely understand it, but

basically it means that you find perfection in imperfect things.

This sort of philosophy is in Iwagumi very, very deeply and a very big part of it, placing the rocks in a way that they are actually imperfect.

But when you look at the whole thing in one, then it is perfect, it is balanced, it has harmony.

And this is what Takashi Amano examined by looking at the same spot many, many, many times to see how nature develops that scene over time, To understand how strict these rules are.

I think the most important stuff is that the rocks are actually named.

In an Iwagumi scape, every single piece has its purpose.

It starts out with oyashi, which is the main rock, the parent stone.

Now, this is obviously the biggest stone in the scape.

It should take about 2/3 of the complete weight of the aquarium.

it's very important that it's always offset to one side to follow the rule of thirds.

And in most cases it's slightly tilted and hence starting to create the imperfection by creating imbalance in the scape.

And the secondary stone, the fukuishi, is there to give balance back, but without creating symmetry.

So the second stone, it usually stands against the main stone to create the balance, but

Now, the third type of stone is the soi, which can already be multiple stones, not just one.

These are supporting stones, and by support, I mean physical support and visual support.

These stones don't have to actually touch the main stones.

Obviously they are smaller than the first two stones, usually drastically smaller, so about half the size of the secondary stone.

And they actually again add to the balance and the harmony of the whole layout.

And then there's the fourth type of stone, which is suteishi.

And again, these can be multiple stones and.

And it translates into sacrificial stone.

Now, these stones are sometimes not even visible by the end.

Again, they have the purpose in the main visuals, but

it's not a problem if later on the plants actually hide them or they just disappear in the process of nature taking over the space that we provided for it.

There is a misunderstanding about Iwagumi saying that you can only use three stones and then the sacrificial ones.

There can be as many stones as you want in an iwagumi, as long as they follow these actual rules.

But it's very, very important that you need to use an odd number of stones.

When you have even number of stones, it creates symmetry in your mind.

Using odd number of stones is very, very important aesthetically in any Iwagumi.

And actually I think in any kind of aquascape, and

we're going to get into this later on, that these rules, even though we don't follow them word by word in other types of aquascaping, or in aquascaping in general, a lot of this stuff actually reflects in any kind of aquascaping.

Now, looking at nature and examining what nature does is important because we are looking for flow in an aquarium.

And I'm not talking about the water flow created by our filters.

I'm talking about a visual flow and that exists in nature.

So when you are putting hardscape elements in a tank, you need to think about how the flow goes through the tank.

And again, an iwagumi scape itself can represent huge mountains, or it can represent just a small part of A riverbed.

If I look at this tank, it's obviously not a mountain, is it?

This could represent distant mountain range achieved.

Now, second, very important part of Iwagumi is minimalism, both in the stones, and

So usually in a classic Iwagumi scape, you get one or maximum three species of plants.

Usually there is a big carpet all around the tank.

And then as secondary plants, you can sometimes see small bushy plants like staurojoin repens in the cracks in between the rocks.

If you have two pieces of rocks behind each other and you have the same plants going in between them, then they are closed.

But if you put different kind of plant in between, then that creates layers for you.

And then your mind thinks that the rock behind is actually further away.

And then the third would be something in the background.

Especially in a riverbed scape, you could have some kind of long grass that represents how the riverbed starts going upwards and starts going out of the river.

Actually, every single plant has its purpose, just like the rocks in the new moonscape.

So if I want to summarize what a classic Iwagumi is, it's balance created by imbalance and imperfection, it's flow and it's minimalism.

And that's actually what attracted to me into aquascaping.

All that said, let's look at a few examples.

So here we have what I talked about, the riverbed, we have the main stone, the secondary stone.

And these are actually already especially this one, because you can only see this in the reflection.

These number fours are the sacrificial stones.

I'm sorry, I'm not going to write to you the Japanese names because, well, I don't want to now again, and

This is again physical support as well, because this part of the soil wouldn't stand if I didn't have this type of weight in front of it.

And then the sacrificial stones, these can be considered classic Iwagumi scapes.

You can't say which one is the main stone or the secondary stone, because this is actually made from multiple stones.

This piece, I think it's actually three pieces of stones, but all together they create a main stone.

I don't even know how many stones, but definitely multiple ones would be my secondary stone.

The whole thing together, visually, it creates a secondary purpose.

And then I have supporting stones here and I have sacrificial ones all around the scape.