Yes, ceramic is safe for fish tank use. It is an inert material that doesn't release harmful substances into the water. Ceramic decorations and substrates are popular choices for fish tanks due to their durability and ability to mimic natural environments. They are easy to clean and won't alter the water chemistry. Ceramic materials can provide hiding places and surfaces for beneficial bacteria growth. However, be cautious of sharp edges on ceramic items that may harm the fish. Properly inspect and clean ceramic decorations before adding them to the fish tank. Regular maintenance and monitoring of water parameters are essential to ensure a healthy environment for your fish.