Why the Fish?
The fish was an early symbol of Christian faith that endures to our present time.
According to historical records, it could be dangerous, particularly during the time of the early church, to identify yourself as a Christian. The simple symbol of the fish was the key to safety. When meeting someone new, you would draw a single arch in the sand. The second person would complete the drawing of the fish by drawing the second arc, if the second person was not a Christian, the ambiguity of the half symbol would not reveal the first person as a Christian.
There are several reasons why we believe fish symbol was chosen besides its obvious simplicity. The fish, unlike a cross, would not be an obvious Christian symbol to persecutors. Also, Jesus' ministry is associated with fish. Several disciples were fisherman and He said that He would make them “fishers of men”. A fish is also a symbol of baptism, since a fish is at home in the water.
As Jesus walked beside the Sea of Galilee , he saw Simon and his brother Andrew casting a net into the lake, for they were fisherman. “Come, follow me”, Jesus said, “and I will make you fishers of men.” At once they left their nets and followed him. Mark 1:16-18