Dragon stone or Ohko stone is a popular rock that’s often used in aquascaping aquariums and terrariums.
But is Dragon stone safe to use in your fish tank? Does this stone change the aquarium water chemistry? And where can you buy Ohko stone?
Read this guide to learn everything you need to know about Dragon rock!
What is Dragon rock?
Dragon stone or Ohko stone is a textured stone named for its pitted, scaly, reptilian appearance that resembles a dragon’s skin. For that reason, many people assume that the rock is unnatural in origin.
However, Dragon rock is actually composed of clay, silt minerals, and organic matter that has been compressed by various geographical processes to form a sedimentary stone.
The rock’s rugged appearance and resemblance to petrified wood make it a firm favorite with many hobbyists and aquascapers. You can find Ohko stone in olive green or brown, depending on the ratio of organic matter to clay content.
Dragon Stone Origins
Dragon stone was originally harvested from lake shores and other water bodies in Japan. However, as you can imagine, these rocks take millennia to form, so they are pretty rare, not to mention expensive!
Fortunately, you can obtain artificially created Dragon stones that are produced in the UK, Canada, and Utah. These stones are readily available and much less pricey than genuine Japanese natural Dragon stones.
What Do Aquarium Dragon Stones Look Like?
As mentioned above, the Dragon stone gets its common name from its scaly, rugged texture and naturally pitted and scarred surface.
Naturally occurring Ohko rocks are shaped and sculpted by water, which creates many tiny holes, crevices, and riffles in the soft parts of the rock’s surface.
The Dragon rock you see in fish stores is usually green, greyish-blue, or mossy brown in color. However, the rarer Japanese rocks can be more brightly colored, being yellow, red, and even orange.
Using Dragon Stone in Your Fish Tank
Many hobbyists use Dragon stone as the main decorative element in their fish tanks.
The stones’ rough surface provides the perfect attachment medium for many species of aquatic plants. Simply use some fishing line or thin wire to fix the plant to the rock, and let nature do the rest.
You can also incorporate Ohko rock into pretty much whatever hardscape structures you want to create by using aquarium adhesive to fix the rocks securely into position.
Dragon stones are pretty versatile, as the rock’s soft sections make it quite easy to break the main piece into smaller stones. To break a large chunk of Dragon rock into smaller pieces, all you need to do is wrap the stone in a towel and hit it with a heavier object.
But you don’t want to risk destroying your expensive Dragon rock completely. So, you might prefer to take a safer route and use a chisel to gradually nibble away at the stone until you get a rock of the perfect size and shape.
How Do I Prepare Dragon Stone for My Aquarium?
Preparing the Dragon stone before adding it to your fish tank is important.
Although Dragon rock doesn’t alter your aquarium water’s pH, the tiny pores, cracks, and uneven texture of the stone’s outer surface can trap dust and dirt.
That dirt could import harmful bacteria into your tank and will almost certainly make the water cloudy until your filtration system removes it.
To clean the Dragon rock:
- Begin by filling a clean bucket with cold water and thoroughly rinsing the rocks to dislodge any superficial surface dust and light debris.
- Now, use a garden hose with the water under medium pressure to flush any remaining muck from the holes in the Dragon rock. Remember that this is a soft rock, so don’t use too much force, or you could damage the stone.
- Inspect the rock carefully to see if any bits of debris are trapped or stuck in the holes. Use a soft toothpick or a wooden skewer to gently prise out debris.
- Rinse the rocks under a tap or hosepipe until the water runs away clear, and all traces of dirt or scraps of stone are gone.
- Make up a solution of nine parts water to one part household bleach. Soak the Dragon rock in the solution for ten to 20 minutes to kill off any bacteria or parasites that might be clinging to the rock. That’s especially important if you took your Dragon rocks from another tank.
- Finally, rinse the Dragon stones thoroughly in dechlorinated tap water to remove all traces of bleach before you add them to your tank.
Note: Do not use harsh chemicals when cleaning Dragon rocks. Chemicals can damage the soft stone or soak into the rock, only to leach out into your aquarium, potentially harming your fish.
What Are the Benefits of Using Dragon Rocks in the Aquarium?
There are quite a few benefits to using Dragon stones in your aquarium.
Dragon Stones Look Great!
First of all, it goes without saying that these strange-looking rocks look spectacular in the aquarium!
You can leave the Dragon stones to do the talking by using them as a focal point in a minimalist setup with just a few eye-catching fish. Alternatively, you could use the rocks as an anchoring point for your favorite aquatic plants.
Dragon Rocks Don’t Affect Water Chemistry
Since Ohko rocks are inert, they won’t break down or decay in your aquarium unless you blast the stones with very high water pressure. That makes Dragon stones one of the safest aquarium decorations you can buy.
However, to be safe, we recommend that you position the Dragon rocks in a spot where they won’t be directly exposed to the filter outlet flow.
Unlike limestones, corals, and other carbonates, Dragon rocks won’t alter the pH in your tank. That’s important in tanks containing fish and other livestock that are highly sensitive to fluctuations in water parameters.
Dragon Stones Provide Hiding Spots For Fish
Many nano fish are shy and like to have plenty of hiding spots to dash to when they feel threatened.
The Dragon stones’ scaly, pitted surface provides lots of holes and caves where very small fish, fish fry, and shrimp can hide when they feel the need to. If you add plenty of lush planting to the rocks, you’ll have created myriad hiding spots for your tiny livestock.
You can also use Dragon rocks to create natural boundaries for territorial fish species, such as bettas. That can prevent disputes over territories and help to maintain harmony in a community tank of semi-aggressive and peaceful species.
Dragon Rocks Provide Anchoring Places for Aquatic Plants
The rough, pitted surface of the Dragon stone makes an excellent attachment point for many species of aquatic plants, including Anubias and Java fern, that extract the nutrients they need from the water column.
That’s one of the reasons these stones are such popular aquascaping rocks.
In addition, once they’re established, the plant’s fibrous root systems help to bind the stones firmly together, preventing them from becoming dislodged or damaged.
What Are the Downsides of Using Dragon Rocks in the Aquarium?
Unfortunately, there are a few disadvantages to using Dragon stones in your aquarium setup.
Dragon Rocks Trap Dirt
Although the Dragon rock’s scaly surface looks fantastic, all those holes and pits readily trap organic matter, including fish waste, leftover food, and general detritus.
Over time, that matter will decompose, releasing toxic ammonia into the water and placing an extra burden on your filtration system.
When carrying out routine weekly maintenance work on your fish tank, you’ll need to use an aquarium vacuum cleaner to suction any debris from the holes in the Dragon rock.
However, we recommend that you periodically remove the Dragon rocks and clean them as described earlier in this article.
Your Livestock Could Get Trapped!
Although Dragon rocks can provide excellent shelter and hiding places for shrimp and tiny fish, your livestock can sometimes get trapped inside the rock.
However, you can overcome that risk to some extent by selecting simple rock formations that have larger holes the fish can easily get in and out of.
Even so, it’s worth conducting a daily headcount of your pets and checking the stone if anyone is missing to ensure none of your fish have become trapped inside the rock.
Dragon Stones Can Be Fragile and Prone to Damage
Dragon stones are not the cheapest tank decorations you can buy, and they are also quite fragile and easily damaged.
As mentioned above, Dragon stones contain fresh clay, and that clay composition can leave the stones prone to chipping and crumbling. That’s important to know if you plan to use the stones to create dramatic aquarium landscapes that could collapse and harm your fish.
Always use aquarium glue to fix the rocks firmly together in a reef structure. If you want to create large-size vertical rock structures, you must ensure that you wedge them securely in place to prevent accidents.
Thanks to its popularity, Dragon rock is readily available from most good fish stores and pet stores that have an aquarium section.
Alternatively, you can buy Dragon stone from several reputable online suppliers, including Amazon, LiveAquaria, or FlipAquatics.
In this section of our guide, we answer some of the questions most often asked by hobbyists about Dragon rock.
Q: Is Dragon Rock Good for Aquariums?
A: Dragon rock is safe to use in your fish tank. The craggy stone won’t affect your aquarium water, looks spectacular when integrated into your aquascape, and can provide a perfect rugged platform for aquatic plants to latch onto and grow on.
In addition, shrimp, shy fish, and fish fry can find shelter within the rock’s folds and crevices.
Q: Does Dragon Rock Affect pH?
A: Dragon rock is pH neutral, so it shouldn’t have an adverse effect on the water chemistry in your fish tank.
However, the rock’s structure can trap loose clay and dirt, which could lower the water’s pH. To prevent that from happening, you need to soak and clean the stone before adding it to your aquarium.
Q: Do I Need To Boil Dragon Stone for the Aquarium?
A: You don’t need to boil pieces of Dragon stone before adding them to your aquarium. Boiling this soft stone can cause it to crack and fall apart.
Q: Does Dragon Stone Affect Your Aquarium Water?
A: Dragon stone should not affect the water chemistry in your fish tank since the rock is inert.
However, the pores and rugged topography of the pieces of stone can harbor dust and dirt. So, we recommend washing and cleaning the rocks before adding them to your aquarium, as outlined earlier in this guide.
Q: Does Dragon Stone Dissolve in Fish Tank Water?
A: Dragon stone won’t dissolve in your aquarium water. However, since the rock is comprised of clay, it is quite fragile and will break relatively easily, so be careful when handling the rocks in Dragon stone setups.
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Ohko rock is a beautiful natural stone with a unique scaly texture that is used by many aquarists to create interesting hardscapes and Dragon stone sculptures in the aquarium.
But despite its rugged appearance, this is a delicate aquascaping stone that is easy to split into smaller pieces if required.
Dragon stone hardscapes make an excellent anchor point for plants and a perfect hideout for shy fish.
However, Dragon stone structures must be regularly vacuumed to remove bits of organic waste that will otherwise gradually decompose, releasing ammonia into your aquarium.