Marina Decorative Aquarium Gravel – Black (1 lb) – A 1-pound bag of jet black aquarium gravel for a sleek and sophisticated substrate. The gravel pebbles are epoxy-coated to ensure they are smooth and inert, meaning they won’t alter your water chemistry. Black gravel is great for making the colors of your fish and plants stand out dramatically. You can use this gravel to fully line the bottom of a small aquarium or as a contrast accent in larger tanks. It also serves the functional purpose of anchoring plants and providing surface area for beneficial bacteria.