Ohko Stone (Dragon Stone)

The hardscape is essentially the backbone of every vivarium.

Having rocks and wood provides a natural environment as well as shelter for inhabitants to find comfort and security within.

Ohko Stone is arguably one of the most sought-after vivarium rocks used as hardscape material in recent times.

This guide will provide a full understanding of Dragon Stone and further explain why it is currently so high in demand.

Quick Stats:
Traditional Name Ohko Stone
Common Names Dragon Stone
Origin Japan
Habitat Lakes, ponds & Seashores
Color Greenish-brown
Density (g/cm3) 1.83g – 2.45g
Hardness 2 – 3
PH Impact Neutral (No Effect)
Elemental Type Sedimentary Rock (Clay)

What Is Ohko Stone?

Ohko Stone is a clastic sedimentary rock comprised of clay minerals and other small bits of organic matter that wash up from passing waves of water.

This rock is also commonly referred to as Dragon Stone due to its scale-like appearance.

Due to its clay material, this type of stone is generally light when compared to other types of aquascaping rocks.

Dragon Stone is a type of mudstone that has a unique formation only found in a few parts of the world.

Dragon Stone Aquascape Tips

Dragon Stone Facts

Even though Ohko Stone is a rare stone to find in many parts of the world, Its mineral makeup is not.

This stone is essentially a mudstone and forms very similar to other sedimentary rocks found throughout the world.

The look of this stone will vary based on the location it’s harvested as well as the part of the structure it is broken off from.

Many inhabitants sharing an enclosure with this type of hardscape will appreciate the many crevices formed in this rock.

It makes a great hiding place for smaller animals as well as a good anchoring source for vivarium plants to latch on to.

A final takeaway to keep in mind for this rock is it has little impact on the environment, making it ideal for all types of vivariums.


Ohko Stone is a very distinctive rock to distinguish.

This makes it rather easy to identify when searching for a promising source to use in an aquascape.

The color of the stone will vary due to a number of environmental influential factors.

Dragon Stone, for the most part, will have a greenish-brown color to it.

This is due to the mixing of clay that gets comprised over time by waves of water impacting its structure as tides brush up against the hard surface of cliffs.

Over time, the sun bakes layers of clay along with other micro-organisms formed over the top of the surface of Ohko Stone through years of consistent exposure to weather.

The porous detail dragon stone exhibits also vary but can generally be summed up to a few key factors.

The holes and crevices established throughout the sedimentary stone are contributors to high-pressure tides penetrating the not-yet-hardened parts of the rock.

The loose debris falls out of the stone leaving it with these unique indentations found within and around Ohko Stone.

Another recognizable indication of this rock is its weight.

True dragon stone is noticeably light in density and rather fragile to work with.

This makes it great to work within aquascaping for a number of reasons.

Many hobbyists deliberately use this material to stack high in structure.

Thus, building taller hardscapes that would normally be a potential danger to inhabitants if tipped over or collapsed due to overweight.


The origin of the Dragon Stone covered in this article here is that of Japan.

Shores surrounding lakes, ponds, and seas are lined with this diverse stone.

Decades of weathered aging make this rock a scarce material to harvest and will justify the high value set for Ohko Stone.

Other areas around the world like Utah, Canada, and The United Kingdom also spawn similar-looking rocks available in today’s market.

The rocks harvested from areas other than Japan will look noticeably different in structure as well as color.

Environmental Influence

For the most part, Ohko Stone will have no real impact on the environment it is placed within.

This is ideal for freshwater aquariums that require a delicate balance in water parameters.

One thing to note though, uncleaned Dragon Stone can house many types of external deposits.

This accumulation of debris could, in fact, warrant a potential influence on the habitat though…

So be sure to check for those impurities and remove them if necessary.

Vivarium Preference

Ohko Stone is an inert rock, meaning it will not have much of an impact on the water it is placed in.

With that being said, it will hold up better in acidic enclosures that keep a PH level under seven.

Rocks composed of clay and organic minerals always do better in freshwater aquariums, ripariums, or tropical terrariums.

Slow weathering of the stone will leech minerals that would benefit plant life in these types of enclosures.

Dragon Stone is a very popular rock to use in simple design enclosures like iwagumi-themed setups.

This hardscape should be used as the centerfold of your tank being placed slightly offset from the center of your terrarium and/or aquarium.

Ohko stones can be combined into larger structures as well as broken down into smaller pieces depending on the intended use of the rock.

It can be placed fully submerged within a freshwater establishment or set above land in a terrarium of any type.


There are a number of advantages Ohko Stone offers when being used in a vivarium.

It has virtually no influence on its surroundings making it great for freshwater aquariums that house PH-sensitive plants and animals.

As mentioned earlier, Dragon Stone is a very lightweight rock to work with.

Not only will that allow for larger hardscapes to be constructed within an enclosure…

But customizing the very shape of the hardscape will be simple to manage since this lightweight rock breaks apart easier.


The downside to working with such a light sedimentary is its durability.

Dragon Stone can be a rather fragile stone to work with compared to other hardscaping stones.

It won’t exactly melt in your hands but enough care should be taken to prevent accidental dropping or excessive cleaning (which will wear the stones down to smaller less desirable sizes).

Another thing to look out for is excess soil trapped within the holes of Ohko stone.

If not properly cleaned, this matter could potentially have some type of effect on the vivarium. S

ome weathering may occur in environments with high-flowing water.

Buy Ohko Stone

Ohko Stone can actually be quite difficult to come by if you live in a part of the world that does not have a steady supply of it accumulating nearby.

Luckily, we were able to find a good source of it available on Amazon.

When buying dragon stone, consider the source and be sure it is what is listed in the description.

No two pieces will look alike but they should still have many of the characteristics listed in this article

The stones may or may not come pre-cleaned so be sure to give it a quick rinse and test for any impurities that may still be present on the stones.

Click the image below to find out more about the current price and other relative info:

Dragon Stone Recommendations

When it comes to working with Ohko Stone for the first time, there are a few things worth keeping in mind.

What kind of pieces you have and how much of them should be used are important factors.

Preparing this stone for an enclosure is also a valuable step that will ensure longevity.

Also, making sure there aren’t unwanted elements tucked within this stone will also aid in preventing unwanted fluctuation of the custom habitat will also be recommended.

Here are a few steps below to better understand the management of Dragon Stone:

Cleaning Ohko Stone

In most cases, newly acquired Dragon Stone will need slight preparation before going into a vivarium.

This will matter more for aquariums rather than terrariums since unclean stones will cause water to change color.

Begin by placing stones in a bucket of cold water.

Lightly rinse each stone thoroughly with a medium-pressure hose.

Use a bamboo skewer to assist with breaking up debris trapped in small crevices.

Repeat this process until you are able to place stones in a clean bucket of water and observe no noticeable change in color.

Avoid using chemicals or strong water pressure so that the rocks aren’t worn down drastically and lose their aesthetic.

Breaking Ohko Stone

Dragon Stone is a fairly easy rock to break into smaller pieces if needed.

In fact, a little too easy!

In many cases, the hobbyist will simply bash a towel-covered piece of rock with a large hammer.

This is great for breaking stone into lots of tiny pieces of rock…

The downside to this is the potential pile of an undesirably crumbled pebble.

Another way that I much prefer is with a chisel.

Chiseling off parts of the rock is a more controlled way to break Ohko stone into desirable pieces.

No matter which way the rock is broken up, make sure to wear safety goggles because parts of the rock will go air born.

Also, reclean rocks as needed once they are broken.

Rocks Similar To Ohko Stone

When designing a new enclosure for the first time, it would be best to stick with one type of stone to use as a hardscape.

Furthermore, this type of rock can be hard to come by depending on where you are located in the world.

If, for any reason, you find Dragon stone difficult to acquire, or simply want to consider something different…

There are a wide variety of stones to contemplate.

Here are some other types of stones one might find are worth taking a look at in the place of Ohko Stone:

Petrified Wood "Fossil Wood" Hardscape Guide
Sandstone "Quartzarenite Rock" Hardscape Guide
Dolomite "Elephant Skin Stone" Hardscape Guide


Dragon Stone has always been one of my favorite aquascaping rocks to work with.

It has no real effects on the enclosure and it’s completely safe to have around inhabitants.

This sedimentary stone adds a level of diversity to a vivarium that is unmatched by any other type of hardscape.

It can be a rather expensive stone to acquire…

But in my opinion, totally worth the money and a very worthy investment.

If you have never considered using this stone before, would you consider it now that you know a bit more about its use in popular aquariums and aquascapes?

How would you rate Ohko Stone on a scale of “totally recommend” and “don’t come near this stuff?” Be sure to let us know down below:

Frequently Asked Questions

Dragonstone is a natural ion exchange medium that can be used to improve aquarium water quality by removing toxic metals and ammonia, as well as balancing PH levels. It can also help remove organic debris from the water, making it ideal for fish and plant health. Dragonstone also helps maintain healthy levels of beneficial minerals and trace elements for fish, plants, and coral in the aquarium.

No, Dragonstone does not change pH. Dragonstone is a type of fireplace stone that is made from natural materials and is created to be heatresistant and durable. It does not contain any acid or alkaline compounds that would change the pH balance in water or soil.

Yes, Dragonstone can raise water hardness. This is due to its high calcium carbonate content, which helps increase the alkalinity of the water. Dragonstone is often used as a natural way to regulate pH and hardness levels in aquariums, as it is nontoxic and won‘t damage delicate biological systems.

Ohko Stone is a type of rock used in aquascaping. It has a rugged, natural appearance that adds character to an aquatic environment. Its porous surface provides a comfortable and secure haven for beneficial bacteria, as well as a great place for small organisms like shrimp and fish to hide. Ohko Stone can also help absorb toxins and ammonia while also adding a unique decorative touch to your aquarium.

Ohko Stone is a type of Japanese rock, otherwise known as Dragon Stone, which is a type of sedimentary rock made up of clay minerals. It is commonly used in aquariums to create aquascapes and is typically a light grayishbrown color. Due to its unique texture, it makes an ideal spot for fish to hide and also helps to provide oxygen in the tank.

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