The Basalt substrate from Aquael is a fine and natural substrate that is distributed in the aquarium. The basalt-black gravel creates impressive contrasts in the aquarium due to its dark shade. The natural substrate does not contain any artificial additives or coatings, which is why it behaves in a water-neutral way and does not release any polluting substances. The substrate has a very fine grain size of 2 – 4 mm and is also ideal for aquariums with shy fish that prefer a dark substrate for camouflage purposes.