In early Christian tradition, the Greek word for FISH (ΙΧΘΥΣ = IChThYS) was an abbreviation for the phrase "Jesus Christ, God's Son, Savior."  Thus:


When Christians suffered intense persecution under the Roman Empire, the symbol of the fish became a way that Christians could quickly identify each other.  For example, according to legend, when two strangers met, during their conversation one might casually draw an arc in the dirt with the toe of his sandal or his walking stick.  If the other person was also a Christian, he would draw a second arc over the first, completing the picture of a fish.

These same Christians met secretly for worship in caves and in tombs, where today we find their fish symbols written on the walls.  Today many Christians still use this symbol to identify themselves as disciples of Jesus Christ.

The fish symbol not only represents our identity with Christ, but it reminds us that Jesus wants us to tell other people about Him.  Some of Jesus' 12 Disciples were professional fishermen.  They didn't fish for sport.  It was their business.  During the night they went out in boats, dropped their nets, and caught as many fish as they could to sell the next morning in the marketplace.   Once, after a night of unsuccessful work, Jesus urged Peter and his partners to go out one more time to deep water, "and let down the nets for a catch."  They caught so many fish, that they nearly sank two boats.  The Disciples were stunned.  Jesus told Peter, "Don't be afraid; from now you will be catching people."   (Luke 5:4-11)