In the modern era, the fish symbol represents Christians and Christianity. It is an ancient symbol that early, persecuted Christians used to mark secret meeting places and identify one another, according to Christianity Today magazine.
In the ancient world, the fish symbol was used to represent fertility. Because the symbol was common, early Christians used the mark without raising suspicion. Legend has it that an early Christian drew half of the symbol when meeting a new person. If the stranger completed the other half of the symbol, both individuals knew they were free to discuss their faith. Modern-day Christians often apply the fish symbol to their vehicles or business signage to indicate their belief system.