Features: Multifunctional Design: This black fish cave is suitable for most fish, shrimp, crabs, goldfish, and other aquatic organisms. It not only protects fish and shrimp from predators, providing a sense of security, but also aids in reproduction, protecting fish eggs and fry from being eaten by larger fish. It also makes it easy for you to observe and catch your fish. Stabilizing the Pond Bottom: The koi castle can hold down the silt, reduce the stirring up of bottom mud, make the water clearer, and provide habitats for benthic small animals (shrimp, snails), forming a small ecosystem. Specifications: Material: aluminum tube, fiberglass mesh Color: black Size: about 24 x 14 x 9 inches Package includes: 1 x fish pond cave Notes: Manual measurement, please allow slight errors on size. The color may exist a slight difference due to different screen displays