The Ohko stone is also referred to as the dragon stone. Originally, it was found near Japanese lakes, the seashore, and ponds. Water erosion caused ripples or holes in the stone and then they got hardened from exposure to the sun. The stone has also been located in other parts of the world such as the UK, Canada, and the United States.
The Ohko stone resembles the scales of a dragon and they are normally greenish-brown in color. They are also lightweight if we were to compare them to other types of stones. The ripples found on the stone create mini caves that anchor plants and plants, which is what most fishes prefer.
What you need to know is that these stones come with soft clay and debris within the craters. Most sellers do not clean them out. So as to have the best crevices, then you need to prepare the stones before using them. You can start with pressure washer making sure that it is not too strong so that it does not destroy them. The water does the trick of clearing all the crevices effectively.
Ohko stones have a neutral pH. This means that they do not alter anything within your aquarium. They are therefore suitable for all types of fish.