Black volcanic rock is an excellent choice for aquariums, both for its natural aesthetics and its beneficial properties. Composed of solidified basalt or lava, it is porous, which encourages colonization by beneficial bacteria, aiding in the biological balance of the pond.
 It is ideal for freshwater aquariums and can be used to create natural scenery, fish hiding places, and plant supports. It generally does not affect water parameters, but it is always recommended to rinse it before adding it to the tank to remove dust residue.