The basalt substrate from Aquael is a thin and natural substrate that is distributed throughout the aquarium. The gravel in basalt-black color creates striking contrasts in the aquarium due to its dark hue. The natural substrate does not contain artificial additives or coatings, making it neutral in relation to the water and preventing the release of pollutants. The substrate has a grain size of 2 - 4 mm and is also ideal for aquariums with shy fish that prefer a dark substrate for camouflage. The rounded edges of the processed basalt gravel ensure safe use and prevent injuries to living creatures on the substrate floor.