Stone
Dragon Stone
Also called Ohko stone, Ohko
By Mike Elmira
TL;DR, Dragon Stone
Dragon stone, or Ohko, is the tan-brown stone riddled with holes and craggy hollows. It is inert, so it leaves your water chemistry alone, which makes it the safe default for planted and shrimp tanks where seiryu would cause trouble. The texture is perfect for tucking moss and small plants into, and it looks great aged. Give it a good rinse first, since the softer clay can shed fine grit.
What it looks like
Warm brown clay stone, deeply pitted with holes and channels. The texture catches light and takes moss and small epiphytes beautifully.
What it does to your water
Inert. It does not measurably change pH or hardness, so it suits soft-water tanks, shrimp and blackwater scapes without any of the buffering that seiryu brings.
How to prepare it
Rinse and gently brush off loose clay and dust, it can crumble a little at the surface. No soaking or boiling required.
Using it in a scape
A favourite for planted layouts and nano scapes. The holes are made for wedging moss, bucephalandra and small crypts, and it ages into a natural, weathered look.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Does Dragon stone affect water parameters?
No. Dragon stone is inert, so it leaves pH and hardness alone. That is why it is the usual pick for soft-water and shrimp tanks where a calcareous stone would cause problems.