Aquascape®️ 78160 Black Decorative River Pebbles. Aquascape Decorative River Pebbles are ideal for enhancing a wide variety of water features and gardens. These unique decorative stones are hand-polished, smooth, and pre-washed, making them the perfect choice for you to complete your project. Each stone measures approximately three to five inches in size, and the easy-to-carry 22 pound bags make them ready for transport. Each bag covers approximately 1.5 square feet of surface.