Every pets lovers knows that decorations and aquarium substrates not only look great, but also affect the environment of our fish. Tunai Lava rock is 100% natural and does not affect the pH of water, nor its cloudiness. It is suitable for all types of aquariums. Great natural base for building block for aquariums with stone and rocky decor, creating beautiful backgrounds, hiding spots, substrates. that are a kind of shelter for fish. The dark color combined with the irregular shape of the rock contrasts perfectly with the green ambience of plants and with the light ground in the rock aquariums. It is perfect for plant tanks or shrimpariums. It has a porous structure which enables an easy attachment of different types of plant mosses. Please rinse in warm water before placing it in the aquarium. Large Lava Rock it measures on average 4" - 7". PLEASE NOTE: The lava rock will vary in color from brown to black.