Your fish will love to rock with the Penn Plax Rock Stack Style 4 Aquarium Decor. Not like rock "n" roll rocking but just kind of hanging out rocking. It"s beautifully detailed and crafted, so it"ll look great in any underwater setting. It"s crafted of non-toxic, fish-safe resin. * Made of non-toxic and fish-safe resin * Intended for both fresh and salt water * Artistically designed to bring a realistic appearance * Brings a natural environment for your aquarium * Dimensions: 10L x 3.5W x 5H in.