Seiryu stone in nature aquascape

Seiryu Stone in your Aquarium: The Ultimate Guide for 2022

When it comes to your aquarium, one of the most important things you can do is provide your aquatic pets with an environment that mimics their natural habitat. Seiryu stone creates a beautiful, natural-looking environment for your fish. It is no surprise they’re one of the most popular aquarium hardscape items!

In this guide, we will explore the ins and outs of seiryu stones, including selecting the best stones for your aquarium, breaking seiryu stones, acid treatment options, and more. Our favorite seiryi stones are the Pisces 17lb Seiryu Rock for Aquascaping, Aquariums, Terrariums, Vivariums. They’re a fun way to change up your current setup especially if you have basics like gravel or sand and want to make things a little more structured.

Let’s dive in!

Our Favorite Options:

What Is Seiryu Stone and Why Should I Use It?

Seiryu stone is named for the “Azure Dragon,” a mythological constellation with blue scales, which likely inspired naming this stone. Seiryu Stone is originally from Japan.

It became popular when the world-renowned aquascaper Takashi Amano started incorporating the stone into his Amano (nature) and Iwagumi aquascaping styles. Since then, Amano’s famous Sieryu stone usage has increased the stone’s popularity exponentially, resulting in worldwide sales.

Because of the high demand for these stones, Japan has made it illegal to export Seiryu stone from Japan in order to protect their supply. This means that there are a lot of fake Seiryu stones floating around. For example, a good portion of the Seiryu stone for sale outside of Japan is actually Ryuoh Stone. Ryuoh tends to be more slate in color with less white marbling. This can be a good alternative if you can’t find or afford seiryu stone.

Seiryu stone in nature scape

Seiryu stones come in various colors, from deep blue to blackish grey. The color range is dependant on acid treatments. They range in size from quite small (1-2 inches) to very large (20+ inches). It has a layered appearance with jagged edges that provides a lot of visual drama and contrast. It also has calcite veins running through it, amping up the contrast. This stone is popular because it’s aesthetically pleasing and easy to use.

When purchasing Seiryu Stone, we recommend purchasing about 1 to 2 pounds of rock per gallon of water in your tank as a starting point.

What is the Best Seiryu Stone? Top 3 Best Seiryu Stone for 2022

Best Seiryu Stone Options:

SevenSeaSupply 5 lbs. Seiryu Stone Rock Aquarium

Seiryu stones are some of the most popular hardscape stones for good reason. They look great in any tank. This option will cover 5 pounds of Seiryu stones and they will make an effort to offer a mix of shapes and sizes. However, 5 pounds won’t go very far in a larger aquarium, so make sure to order multiple batches if you have a larger tank to fill. Alternatively, if you want to experience with a small amount of stones, or have concerns about pH shifts, starting with a small amount could be a good idea.


  • 5 pounds of Seiryu stones


  • Good for experimenting with how the stones look in your tank
  • Looks good with carpeting or short growth plants


  • Not enough stones for a large tank, requires multiple orders
  • Some users report stones require cleaning before using

Pisces 17lb Seiryu Rock for Aquascaping, Aquariums, Terrariums, Vivariums

Our Pick
Seiryu Stones for Aquascaping and Aquariums

What We Like

  • They add to the aesthetic of your tank
  • They help provide places for your aquatic critters to hide
Check Price on Amazon

Similar to the option above, but 17 pounds worth of stones. These stones come in a mixed size and shape grouping, so you have a lot of variety for designing for your tank. Stones are heavy so the consensus seems to be roughly that 17 pounds is about as many stones as you’d want for a 10-gallon tank. This is also a great option for aquarists that want a little more choice in their stones when working on smaller tanks. For anything bigger than 10 gallons, you’re going to need more than one order of these.


  • 17 pounds of Seiryu stones


  • Typically enough stones for smaller tanks (10 gallons or less)
  • Shipping price is reasonable given heavy nature of package


  • Not enough stones for a large tank, requires multiple orders
  • Some users report stones require cleaning before using

CURRENT USA Seiryu Stone Collection 11 Pieces, up to 48″ Aquariums

Seiryu Stone is an incredibly popular type of stone in the world of aquascaping, often being used as an aesthetic focal point. Seiryu Stone brings a realistic, natural look to any aquarium. However, they can also change water parameters in ways that might not be appropriate for fish and invertebrates. This artificial stone set has the look of real Seiryu stones, with each piece being hand-painted for a unique appearance. The real benefit here is that they are also safe for all aquatic life as well as freshwater plants. Best of both worlds!


  • Comes with 11 molded stones to make mixing and matching easy for your aquarium
  • 100% aquarium safe


  • Safe for all fish and invertebrates
  • Lightweight
  • Attractive aesthetics
  • Variety of sizes and combinations


  • Have small crevices within the stone to help them sink, could be dangerous for shrimp
  • Not the “real deal”

Aquascaping Dragon Ohko Rock Kit – Decorative Aquarium Rocks – 25 Gallon Kits

Full disclosure – these are not Seiryu stones. We have included these as a common alternative to Seiryu stones that are also very popular and beautiful. Like the other options on this list, this is a mix pack of sizes and shapes so you will have plenty of stone options to choose from while decorating. We love the natural brown color of these stones and think they pair really well with natural gravel.


  • 25 pound set of stones – mixed sizes and colors
  • Dragon stone


  • Good alternative to Seiryu stones
  • More brownish in tone than blue and grey Seiryu stones
  • You get a lot of stone for the cost


  • Some reviews report needing to clean the stones before using them

Aquascaping with Seiryu Stone

Aquascaping is the intentional curation of an underwater landscape in your fish tank. It uses many different elements such as live plants, rocks, and driftwood to create beautiful environments. It also uses aquascaping tools to keep everything looking beautifull.

Seiryu stones are often used for aquascaping due to their resemblance to natural rocks one might find in a river setting. Aquascapers use them as key focal points in their tank to create naturally balanced aquariums. They’re also favored because of their color contrast with the green and red aquarium plants typically used in aquascaping.

Seiryu stone works really well in the Iwagumi style of aquascaping. This approach combines carpet plants and stones. The blueish hues of the stones pop against the green carpeting, making the tank very high contrast. Larger Seiryi stones can also be used to creature miniature mountains, making a natural, craggy beauty.

You can also mix and match Seiryu stones with other stone choices. Pagoda rock, ohko stone, granite, and ryouh are all good choices that complement Seiryu.

An additional reason that Seiryu stone is so popular is that it has a porous texture which helps microorganisms in your tank grow. This can be helpful for your fish and plants, as it helps balance the ecosystem.

How to Break Seiryu Stone

Seiryu stones are not typically sold in smaller pieces. Because of this, you will sometimes need to break them down before you can use them in your aquarium. Knowing how to break them properly is important so the break lines look natural. Here are the steps you’ll need to follow:

1) Wear safety googles and gloves to avoid any flying pieces or jagged edges.

2) Use a hammer and chisel to chip away at the stone so you can maintain jagged lines. Cutting the stone directly will create clean lines that don’t look natural.

If you go the clean-cut route, you can always angle the cuts away from the viewer to preserve a more natural look.

Acid Treating Seiryu Stone

Some aquarists choose to acid treat their stones in order to bring out a darker black color with white marbling. For this process, muriatic acid (hydrochloric acid) is used. This acid is easy to find and is available at almost any home maintenance type store.

To do this treatment, first put on your protective gear. You will need both protective eye and hand protection because it will quickly damage your skin. Avoid inhaling the fumes because they will irritate your lungs.

To start the process, immerse the stone in muriatic acid for 5 to 10 minutes until the desired color is reached. After the acid bath, use tongs to remove your stones and place your pieces in a bucket of pure water for 15 minutes. This will neutralize the acid, making it safe to use in your aquascape.

Some people claim that acid treatments neutralize the stones’ alkaline buffering capacity. However, this isn’t true. Even after acid treatments, your Seiryu stones will continue to raise the pH in your tank. So don’t think you can acid treat your way out of higher pHs.

Where to Buy Seiryu Stone

As stated earlier, exporting Seiryu stone outside of Japan is illegal. This can make it challenging to find for purchase. Big box pet stores like PetSmart and Petco don’t readily carry it so you either have to look for specialized aquascaping fish stores locally or purchase online. Do take the time to read reviews to make sure you’re getting the real deal!

Fake Seiryu Stone

Real Seiryu stone can be difficult to get. As mentioned earlier, a lot of the stones sold online are actually Ryouh. Ryouh is pretty similar to Seiryu except it doesn’t have the same blue undertone; it tends to be towards the grey end of the spectrum. It is also often duller in appearance. Both stones will have white marbling so you can’t use the relative presence or absence of this to determine what kind of stone you have,

If you’re on a budget, using Ryouh stones can be a great way to create a beautiful aquascape at a more affordable price point.

Seiryu Stone VS. Dragon Stone

Another common alternative to Seiryu is Dragon Stone. While Seiryu and Ryouh stones can often be difficult to tell apart, Dragon Stones and Seiryu are pretty easy to tell apart. Dragon stone is a brownish, earth-toned rock that often looks pitted. Dragon Stone is very easy to accidentally crush, whereas Seiryu stone is difficult to break apart and requires a hammer and chisel. Seiryu Stones are well-documented in their powers to raise your pH, but the Dragon Stone will not impact the water parameters.

Effects on Water Chemistry

When adding different natural components like rocks, Indian almond leaves, or driftwood to your tank, it is important to understand how they will change the water parameters. At a high level, these stones may slightly raise the pH and the gH of your water.

Does Seiryu Stone raise the pH in your tank?

When using Seiryu stones, you’ll notice an increase in pH.

Fish, plants, and invertebrates (shrimps) can get sick and sometimes even die with the wrong stone choice. Metamorphic rocks, like limestone, marble, and Seiryu stones, tend to impact water chemistry. Specifically, Seiryu contains calcium carbonate, impact the GH and KH of an aquarium. By impacting both of these variables simultaneously, it means the pH will shift and water hardness will increase. Essentially, the stones leach calcium carbonate over time which increases the water hardness.

Some fish, such as certain livebearers and types of cichlids, prefer hard water so they will be jazzed with Seiryu stones. However, if you have species that prefer more acidic waters, you will need to take this into account.

Frequent Water Changes

If you have a tank with Seiryu stones, frequent water changes are important. Because the stones are continually leaching, pH maintenance is not a one-and-done type operation. You’ll need to regularly check your water parameters and change out a portion of the water. Frequent, smaller water changes are preferred over larger changes which result in drastic parameter shifts.

Acid Buffers

Another option for buffering is using driftwood, Indian Almond Leaves, or an acidic substrate like peat moss or ADA Aquasoil.

Aqua Design Amano (ADA)’s substrate helps maintain the correct pH range for Cardinal Tetras, Cherry Shrimp, Glass Shrimp and Amano Shrimp, and other inhabitants that tend to prefer more acidic conditions.

The main concern with these options is that adding acids accelerates the release of alkaline agents from within the stone. So while it helps balance the situation, it also means you will need more frequent water changes because your stone will be leaching at a faster rate because of the counterbalancing acids in the water.

Is Seiryu Stone Shrimp Safe?

Seiryu stones are largely safe for shrimp, including ghost shrimp, amano shrimp, vampire shrimp, and red cherry shrimp. You should be aware that Seiryu or any other type of limestone rock will make the water hardness increase which can stress invertebrates if proper precautions aren’t taken. We recommend weekly water parameter checks to make sure everything looks good. We also recommend avoiding stones with sharped jagged edges to keep your invertebrates from accidentally injuring themselves. Overall though, we consider Seiryu stones some of the best rocks for shrimp tank.

Also, if you’re planning on setting up a shrimp tank, check out our shrimp tank guide for all the relevant details.

How do you clean Seiryu Stone?

Seiryu Stones are a low-maintenance aquarium feature. Speaking candidly, they do not need to be regularly cleaned. However, if you’re looking for a way to clean the stones, maybe before adding them to your tank for the first time, you have a few options

  • Quick scrub with vinegar and a toothbrush
  • Boil for 10 months (add them when the water is cold so you don’t shatter them with the rapid temperature change)
  • Soak in a 1:10 bleach solution (one part bleach to ten parts water) for two hours. After the soak is complete, rinse them thoroughly with tap water.


How much Seiryu Stone should I put in an aquarium?

Our general rule of thumb for estimating how many pounds of stone you need is 1-2 pounds of stone per gallon in your tank. For example, if you have a 10-gallon tank, you will likely need between 10-20 pounds of stone. We also advise purchasing on the higher end of that scale so you have some choices between different rocks when it comes time to designing your tank.

What color sand for Seiryu Stone?

The best color substrate depends on your preferences! Seiryu Stone complements both dark and light substrates. Darker substrates will cause the white marbling to pop, whereas lighter substrates will contrast with the entire rock. Up to you!


Now that you know more about seiryu stones, it’s time to get creative! What is your favorite way of incorporating these unique rocks into your aquarium? Do you use them as a decoration or do they serve an important purpose in the tank? We would love to hear more!

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