Dragon Stone (Ohko) in Aquascaping: The Porous Favourite

Table of Contents

• What Is Dragon Stone?
• Key Characteristics
• pH Neutral: The Soft Water Advantage
• Cleaning Dragon Stone: Expect Dust
• Layout Versatility
• Planting Mosses and Epiphytes in Crevices
• Gluing Pieces Together for Structures
• Cost and Sourcing in Singapore
• Frequently Asked Questions

What Is Dragon Stone?

Dragon stone, also known as Ohko stone, is a clay-based sedimentary rock prized in aquascaping for its highly textured, porous surface and warm, earthy tones. Its distinctive appearance — riddled with holes, crevices and undulating ridges — has made it one of the most popular hardscape materials in the hobby worldwide.

The name “dragon stone” comes from the way weathered pieces can resemble the scales, spines and contours of a dragon’s hide. Each piece is unique, and the natural pitting and erosion patterns give every stone a character that would be impossible to replicate artificially.

At Gensou, dragon stone has been a staple of our hardscape inventory for over two decades. We source quality pieces for our customers at 5 Everton Park and use it extensively in our custom aquarium builds throughout Singapore.

Key Characteristics

Dragon stone stands apart from other aquascaping stones in several important ways:

The lightweight nature of dragon stone is a practical advantage in several ways: it is easier to carry home from the shop, it puts less stress on glass panels, and it is simpler to rearrange during the layout process. However, lighter stones can shift more easily if bumped or during vigorous water changes, so securing them properly in the substrate is important.

pH Neutral: The Soft Water Advantage

One of dragon stone’s greatest strengths is its inert nature. Unlike limestone-based stones such as Seiryu, dragon stone does not leach calcium carbonate into the water and therefore has no effect on KH, GH or pH.

This makes it the preferred choice for:

• Caridina shrimp tanks — Crystal red shrimps, Taiwan bees and other Caridina species that require soft, acidic water (pH 5.5–6.5, KH 0–1).
• Discus aquariums — Discus thrive in soft, warm water, and dragon stone’s inertness keeps parameters stable.
• Aquasoil-based tanks — Active substrates like ADA Amazonia are designed to lower and buffer pH downward. Using Seiryu stone works against this, while dragon stone complements it perfectly.
• CO2-injected planted tanks — Without limestone buffering against the carbonic acid from CO2, you get more predictable and stable pH values.

In Singapore, where PUB tap water is already relatively soft (KH 1–3, GH 2–4), many aquascapers prefer inert hardscape to keep parameters low and predictable. Dragon stone is the natural choice for these setups.

Cleaning Dragon Stone: Expect Dust

If there is one thing every aquascaper learns the hard way about dragon stone, it is this: it produces an extraordinary amount of dust. Fresh dragon stone, straight from the bag, will turn a bucket of clean water into opaque brown soup within seconds. This dust is harmless but can cloud your tank for days if you skip the cleaning step.

Cleaning Process

1. Initial soak — Place the stones in a bucket and fill with water. The water will turn brown almost immediately. Drain and refill. Repeat three to four times until the water runs noticeably clearer.
2. Scrub — Use a stiff-bristled brush (an old toothbrush works well for crevices) to scrub every surface. Pay particular attention to the holes and pits where clay dust accumulates.
3. Pressure rinse — If you have access to a garden hose, a strong jet of water into the crevices dislodges stubborn dust that brushing misses.
4. Final soak — Leave the stones submerged in clean water for 24–48 hours. Change the water once or twice. By this point, most of the loose particulate will have been released.
5. Air dry — Allow the stones to dry completely before your layout session. Dry stones are easier to glue and position.

Even after thorough cleaning, you may notice slight cloudiness in your tank for the first day or two after setup. This is normal and will clear once your filter catches the remaining fine particles. A filter floss pad will accelerate the clearing process.

Layout Versatility

Dragon stone’s warm tones and organic textures make it remarkably versatile. It works across every major aquascaping style:

• Nature aquarium — The porous surface and natural weathering patterns evoke eroded hillsides and cliff faces.
• Iwagumi — While Seiryu is the traditional iwagumi stone, dragon stone iwagumi layouts have gained popularity for their warmer, softer character and soft water compatibility.
• Diorama/landscape — The pitted surface reads as rock faces and cave entrances at small scales, making dragon stone excellent for forced-perspective mountain scenes.
• Paludarium — Dragon stone’s lightweight nature and easy workability make it ideal for building land sections above the waterline.

The warm colouration pairs especially well with green mosses, which create a vibrant contrast against the ochre and tan tones. It also complements red and brown driftwood beautifully in mixed hardscape layouts.

Planting Mosses and Epiphytes in Crevices

The holes and crevices that define dragon stone are not just decorative — they are ready-made planting pockets. This is one of the stone’s most practical advantages, allowing you to attach plants directly to the hardscape for a mature, overgrown appearance from day one.

Best Plants for Dragon Stone Crevices

• Mosses — Christmas moss, flame moss and weeping moss can be tucked into holes and secured with a dab of cyanoacrylate superglue gel. Within weeks, they will spread across the stone surface.
• Anubias nana petite — Wedge the rhizome into a crevice and secure with a small amount of glue. The roots will eventually grip the stone on their own.
• Bucephalandra — These slow-growing epiphytes thrive on rock surfaces and the porous texture of dragon stone gives their roots excellent purchase.
• Riccia fluitans — Tuck small portions into the holes with thread or hairnet mesh for a pearling accent.

For detailed techniques on attaching plants to hardscape, see our aquarium glue guide.

Gluing Pieces Together for Structures

Dragon stone’s lightweight and somewhat fragile nature makes it perfect for gluing into larger structures. This technique allows you to create overhangs, arches, cliff faces and cave formations that would be impossible with a single stone.

Gluing Techniques

1. Cyanoacrylate superglue (gel formula) — The go-to adhesive for dragon stone. Apply a generous line of gel superglue to the dry contact surface, press the pieces together firmly for 15–20 seconds, and hold until the bond sets. The glue turns white when it cures, but this is easily hidden by plants or by positioning the joint out of the direct line of sight.
2. Epoxy putty — For structural joints that need to bear weight, epoxy putty (Milliput or aquarium-safe two-part epoxy) provides a stronger bond. Mix the putty, apply to both surfaces and press together. It takes 30–60 minutes to set and can be sculpted while soft.
3. Combination approach — Use superglue for initial positioning (instant hold) and reinforce with epoxy at hidden joints for long-term strength.

Tips for Successful Gluing

• Always glue dry surfaces — superglue bonds poorly on wet stone.
• Test-fit pieces before applying glue so you know exactly where each stone goes.
• Build structures outside the tank, let them cure fully, then place the assembled structure into the aquarium.
• Roughen smooth contact points with sandpaper to improve glue adhesion.
• For tall structures, work from the bottom up, allowing each layer to cure before adding the next.

Cost and Sourcing in Singapore

Dragon stone is widely available at aquascaping and aquarium shops across Singapore. Pricing varies by quality, size and the specific shop.

Approximate Pricing (SGD)

Because dragon stone is lighter than most aquascaping stones, a kilogram of dragon stone yields more visual volume than a kilogram of Seiryu or river rock. For a 60cm tank, 3–6 kg typically provides ample material. For a 90cm tank, budget 6–12 kg.

At our Everton Park shop, we maintain a rotating stock of dragon stone in various sizes and encourage customers to visit and hand-pick their pieces. The beauty of this stone lies in its individuality — selecting pieces in person ensures you get exactly the shapes and textures that suit your layout vision.

Frequently Asked Questions

Does dragon stone harbour bacteria or parasites?

Freshly sourced dragon stone is quarried material, not collected from waterways, so it does not harbour aquatic parasites or problematic bacteria. The thorough cleaning and soaking process described above removes any surface contaminants. There is no need to boil or bleach dragon stone before use — a good scrub and multi-day soak is sufficient.

Can I use dragon stone in a saltwater aquarium?

Dragon stone is not commonly used in marine aquariums because it lacks the porosity and buffering capacity of live rock or dry reef rock. While it is technically inert and would not harm a saltwater system, there are better options for marine setups. In freshwater planted tanks, however, it is outstanding.

Will dragon stone crumble or break down over time in water?

Dragon stone is a fired clay/sedimentary material and is durable enough to last years in an aquarium without significant degradation. However, it is softer than granite or basalt, and rough handling can chip edges or break thin protruding sections. Once placed in the tank, it will remain structurally sound indefinitely. The porous surface may darken slightly over time as biofilm develops, which most aquascapers consider an improvement to the appearance.

How does dragon stone compare to lava rock?

Both are porous and lightweight, but they serve different aesthetic roles. Dragon stone has a refined, sculpted appearance with warm tones and dramatic holes, making it a feature hardscape material. Lava rock is rougher, darker (typically black or dark red) and less visually refined — it is more often used as a functional material (filter media, substrate filler, plant attachment base) rather than a focal-point stone. In terms of cost, lava rock is generally cheaper per kilogram in Singapore.

Find Your Dragon Stone at Gensou

Dragon stone’s unique combination of visual drama, pH neutrality and practical workability makes it the most versatile stone in the aquascaper’s toolkit. Whether you are building a Caridina shrimp tank that demands inert hardscape, crafting a moss-covered cliff face or gluing together an elaborate cave structure, dragon stone delivers.

Visit us at 5 Everton Park to browse our current stock and find pieces that speak to your design vision. Our team has over 20 years of experience working with this stone and can advise on quantities, layout composition and plant attachment techniques. For a fully designed installation, explore our custom aquarium service.