Fish do not shock themselves because their bodies are specialized in such a way that the electrical signals produced by their cells are contained within the cells and do not escape into the surrounding tissues or water. This is achieved through the use of specialized tissues and structures that insulate the electrical signals, preventing them from reaching sensitive areas of the fish's body and causing harm. Additionally, the electrical signals generated by fish are carefully regulated by their nervous system and are only released when necessary for specific functions such as navigation, defense, and hunting. In this way, fish are able to produce electrical signals without harming themselves.