Our Red Slate Ecoscape rock is not only an artistic choice for the home aquarium, but also a safe choice for both fish and plants. Red Slate is a common metamorphic rock that is originally shale or mudstone, and will not interfere with water pH or hardness. Our Red Slate rock is also pre-soaked and will not release excessive tannins into your aquarium water. It comes in a variety of shapes and sizes handpicked by the Ecoscape team to give your aquarium a unique look.