Stone
Seiryu Stone
Also called blue dragon stone
TL;DR, Seiryu Stone
Seiryu is the classic Iwagumi stone, blue-grey with dramatic white veins and sharp jagged edges. The catch that catches a lot of people out is that it is calcareous, so it slowly raises pH and hardness. That is fine for a tank aimed at harder, higher pH water, but it works against soft-water plants and shrimp, and it is worth knowing before you build a whole scape on it. A splash of aquarium-safe acid will fizz on it, which is the quick test.
What it looks like
Angular blue-grey stone with pale calcite seams running through it, and crisp ridged edges that read well in a minimalist scape.
What it does to your water
It contains calcium carbonate, so it dissolves slowly and pushes pH and general hardness up over time. The effect is stronger in soft, low-buffered water. If you are aiming for a soft-water shrimp or blackwater tank, seiryu will fight you; for a harder community it is fine. Test with a drop of acid, it fizzes.
How to prepare it
Scrub it under running water to clear dust and loose grit. No soaking needed, but rinse well so you are not dumping fine sediment into the tank.
Using it in a scape
The go-to stone for Iwagumi and mountain scapes. Its strong lines suit a spare, rocky layout with a carpet foreground. Bury the base so stones look rooted rather than dropped on the substrate.
Seiryu Stone you can actually buy
Supplier photos of real pieces, with the sizes they come in, so you can see the colour and texture before you order.
UNS · Stone
Black Mountain Seiryu Stone
Iwagumi and nature layouts where you want Seiryu shapes in a darker, moodier colour.
3 models
UNS · Stone
Blue Mountain Seiryu Stone
Iwagumi scapes in hard or moderately hard water that want Seiryu shapes with a cooler colour.
4 models
UNS · Stone
Flat Bottom Seiryu Stone
Small cube Iwagumi builds where you want a stable peak without fiddling (S suits 25 cm cubes, M suits 30 cm cubes).
2 models
UNS · Stone
Seiryu Base Stone
Sloped or terraced Iwagumi and nature layouts that need hidden structure beneath the show stones.
1 model
UNS · Stone
Seiryu Stone
Iwagumi and nature layouts in tanks where a little extra hardness is fine, such as most community fish and Neocaridina setups.
5 models
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Does Seiryu stone raise pH?
Yes. It is calcareous, so it slowly lifts pH and hardness, most noticeably in soft water. That suits a harder-water community but works against soft-water shrimp and blackwater setups.
Is Seiryu stone safe for shrimp?
For Neocaridina in harder water it is usually fine. For Caridina, which want soft, acidic water, the hardness it adds is a problem, so most soft-water shrimp keepers pick an inert stone like Dragon stone instead.