World Wide Imports Aqua Terra River Pebbles, 25 lb Natural Gravel 100% Acrylic Clear Coating. Will not alter the chemistry of your aquarium water. Non-toxic. Colorfast Aquarium Stones/Pebbles/Rocks/Gravel - Pure Water Pebbles Fresh & Saltwater Aquariums. Ponds. Terrariums. Gardens. Potted Plants. Vases. Ash Trays. Crafts & Hobbies